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  • 1.
    Bergman, Peder
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Radial Variation of Measured Carrier Lifetimes in Epitaxial Layers Grown with Wafer Rotation2012Ingår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 289-292Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this report we present homoepitaxial growth of 4H-SiC on the Si-face of nominally on-axis substrates with diameter up to 100 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers. Also, local variations in carrier lifetime are different from standard off-cut epilayers. The properties of layers were studied with more focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneous surface morphology and different growth mechanisms.

  • 2.
    Booker, Ian D.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Farkas, Ildiko
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Chloride-based SiC growth on a-axis 4H-€“SiC substrates2016Ingår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 480, s. 23-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract SiC has, during the last few years, become increasingly important as a power-device material for high voltage applications. The thick, low-doped voltage-supporting epitaxial layer is normally grown by CVD on 4° off-cut 4H–SiC substrates at a growth rate of 5 – 10 ÎŒ m / h using silane (SiH4) and propane (C3H8) or ethylene (C2H4) as precursors. The concentrations of epitaxial defects and dislocations depend to a large extent on the underlying substrate but can also be influenced by the actual epitaxial growth process. Here we will present a study on the properties of the epitaxial layers grown by a Cl-based technique on an a-axis (90° off-cut from c-direction) 4H–SiC substrate.

  • 3.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Carrier Lifetime Relevant Deep Levels in SiC2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Silicon carbide (SiC) is currently under development for high power bipolar devices such as insulated gate bipolar transistors (IGBTs). A major issue for these devices is the charge carrier lifetime, which, in the absence of structural defects such as dislocations, is influenced by point defects and their associated deep levels. These defects provide energy levels within the bandgap and may act as either recombination or trapping centers, depending on whether they interact with both conduction and valence band or only one of the two bands. Of all deep levels know in 4H-SiC, the intrinsic carbon vacancy related Z1/2 is the most problematic since it is a very effective recombination center which is unavoidably formed during growth. Its concentration in the epilayer can be decreased for the production of high voltage devices by injecting interstitial carbon, for example by oxidation, which, however, results in the formation of other new deep levels.

    Apart from intrinsic crystal flaws, extrinsic defects such as transition metals may also produce deep levels within the bandgap, which in literature have so far only been shown to produce trapping effects.

    The focus of the thesis is the transient electrical and optical characterization of deep levels in SiC and their influence on the carrier lifetime. For this purpose, deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) variations were used in combination with time-resolved photoluminescence (TRPL). Paper 1 deals with a lifetime limiting deep level related to Fe-incorporation in n-type 4H-SiC during growth and papers 2 and 3 focus on identifying the main intrinsic recombination center in p-type 4H-SiC. In paper 4, the details of the charge carrier capture behavior of the deeper donor levels of the carbon vacancy, EH6/7, are investigated. Paper 5 deals with trapping effects created by unwanted incorporation of high amounts of boron during growth of n-type 4H-SiC which hinders the measurement of the carrier lifetime by room temperature TRPL. Finally, paper 6 is concerned with the characterization of oxidation-induced deep levels created in n- and p-type 4H- and 6H-SiC as a side-product of lifetime improvement by oxidation.

    In paper 1, the appearance of a new recombination center in n-type 4H-SiC, the RB1 level is discussed and the material is analyzed using room temperature TRPL, DLTS and pnjunction DLTS. The level appears to originate from a reactor contamination with Fe, a transition metal that generally leads to the formation of several trapping centers in the bandgap. Here it is found that under specific circumstances beneficial to the growth of high-quality material with a low Z1/2 concentration, the Fe incorporation also creates an additional recombination center capable of limiting the carrier lifetime.

    In paper 2, all deep levels found in p-type 4H-SiC grown at Linköping University which are accessible by DLTS and MCTS are investigated with regard to their efficiency as recombination centers. We find that none of the detectable levels is able to reduce carrier lifetime in p-type significantly, which points to the lifetime killer being located in the top half of the bandgap and having a large hole to electron capture cross section ratio (such as Z1/2, which is found in n-type material), making it undetectable by DLTS and MCTS.

    Paper 3 compares carrier lifetimes measured by temperature-dependent TRPL measurements in n- and p-type 4H-SiC and it is shown that the lifetime development over a large temperature range (77 - 1000 K) is similar in both types. This is interpreted as a further indication that the carbon vacancy related Z1/2 level is the main lifetime killer in p-type.

    In paper 4, the hole and electron capture cross sections of the near midgap deep levels EH6/7 are characterized. Both levels are capable of rapid electron capture but have only small hole capture rates, making them insignificant as recombination centers, despite their advantageous position near midgap.

    Minority carrier trapping by boron, which is both a p-type dopant and an unavoidable contaminant in 4H-SiC grown by CVD, is investigated in paper 5. Since even the shallow boron acceptor levels are relatively deep in the bandgap, minority trap and-release effects are detectable in room-temperature TRPL measurements. In case a high density of boron exists in n-type 4H-SiC, for example leached out from damaged graphite reactor parts during growth, we demonstrate that these trapping effects may be misinterpreted in room temperature TRPL measurements as a long free carrier lifetime.

    Paper 6 uses MCTS, DLTS, and room temperature TRPL to characterize the oxidation induced deep levels ON1 and ON2 in n- and p-type 4H- and their counterparts OS1-OS3 in 6H-SiC. The levels are found to all be positive-U, coupled two-levels defects which trap electrons efficiently but exhibit very inefficient hole capture once the defect is fully occupied by electrons. It is shown that these levels are incapable of significantly influencing carrier lifetime in epilayers which underwent high temperature lifetime enhancement oxidations. Due to their high density after oxidation and their high thermal stability they may, however, act to compensate n-type doping in low-doped material.

    Delarbeten
    1. Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC
    Öppna denna publikation i ny flik eller fönster >>Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC
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    2014 (Engelska)Ingår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, nr 8, s. 4104-4110Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.

    Ort, förlag, år, upplaga, sidor
    American Chemical Society (ACS), 2014
    Nationell ämneskategori
    Kemi
    Identifikatorer
    urn:nbn:se:liu:diva-110278 (URN)10.1021/cg5007154 (DOI)000340080400049 ()
    Anmärkning

    Funding Agencies|The Swedish Energy Agency; Swedish Research Council (VR); Swedish Foundation for Strategic Research (SSF); LG Innotek

    Tillgänglig från: 2014-09-05 Skapad: 2014-09-05 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
    2. Electron and hole capture cross sections of deep levels accessible by DLTS and MCTS in p-type 4H-SiC
    Öppna denna publikation i ny flik eller fönster >>Electron and hole capture cross sections of deep levels accessible by DLTS and MCTS in p-type 4H-SiC
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The effective electron (σn(T)) and hole (σn(T)) capture cross sections of the electrically active deep levels HK0, HK2, LB1 and EM1 found in as-grown, high temperature annealed and oxidized p-type 4H-SiC were measured by deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS) and optical-electrical MCTS and DLTS (OE-MCTS and EO-DLTS) in an effort to determine the potential recombination centers in p-type material. Additionally, we also find the D-center, and the deep levels EH6/7, ON1 and ON2 in our samples, while the levels HK1, HK3 and HK4, reported in literature, are always below the detection limit. We further compare deep level concentrations and the timeresolved photoluminescence (TRPL) measured low injection (τLI) in samples annealed at up to 1920 °C. None of the detected deep levels possess σp(T):σn(T) ratios which could enable them to act as efficient recombination centers in the annealed epilayers, where τLI ranges from 1.2·10-6 s to less than 100·10-9 s. However, a clear anti-correlation between τLI and the EH6/7 concentration is found, which is linked to the main lifetime limiting center in n-type material, Z1/2, via their common origin, the carbon vacancy. Due to their large σp(T):σn(T) ratio, the Z1/2 deep levels are not detected by frontside illumination MCTS in p-type material. We thus conclude that the main lifetime limiting deep level(s) in p-type 4HSiC appear to be located in the upper half of the bandgap and are most likely either Z1/2, or other deep levels of intrinsic or partially intrinsic origin with a similar σp(T):σn(T) ratio.

    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-121542 (URN)
    Tillgänglig från: 2015-09-24 Skapad: 2015-09-24 Senast uppdaterad: 2015-09-24
    3. Carrier lifetime in p- and n-type 4H-SiC
    Öppna denna publikation i ny flik eller fönster >>Carrier lifetime in p- and n-type 4H-SiC
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    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Temperature-dependent time-resolved photoluminescence measurements made in the temperature range from 77 K to 1000 K on free-standing as grown n-type 4H-SiC and p-type 4H-SiC epilayers, which are either as-grown or annealed at 1000 °C, 1400 °C or 1700 °C, are analyzed. The development of the instantaneous carrier lifetime over temperature, calculated from the decay curves of all n- and p-type samples, is found to be identical in the entire temperature range. With increasing annealing temperature only the magnitude of the lifetime in p-type 4H-SiC decreases while the trend remains identical to that in the as-grown n-type sample. Annealing thus only increases the density of the main recombination center which appears to control lifetime in as-grown n- and p-type material. The results implies that the lifetime in all samples may be governed by the same intrinsic defect, which we suggest to be Z1/2.

    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-121543 (URN)
    Tillgänglig från: 2015-09-24 Skapad: 2015-09-24 Senast uppdaterad: 2015-09-24
    4. Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC
    Öppna denna publikation i ny flik eller fönster >>Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC
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    2016 (Engelska)Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, nr 23, artikel-id 235703Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Using medium- and high-resolution multi-spectra fitting of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), optical O-DLTS and optical-electrical (OE)-MCTS measurements, we show that the EH6∕7 deep level in 4H-SiC is composed of two strongly overlapping, two electron emission processes with thermal activation energies of 1.49 eV and 1.58 eV for EH6 and 1.48 eV and 1.66 eV for EH7. The electron emission peaks of EH7 completely overlap while the emission peaks of EH6 occur offset at slightly different temperatures in the spectra. OE-MCTS measurements of the hole capture cross section σp 0(T) in p-type samples reveal a trap-Auger process, whereby hole capture into the defect occupied by two electrons leads to a recombination event and the ejection of the second electron into the conduction band. Values of the hole and electron capture cross sections σn(T) and σp(T) differ strongly due to the donor like nature of the deep levels and while all σn(T) have a negative temperature dependence, the σp(T) appear to be temperature independent. Average values at the DLTS measurement temperature (∼600 K) are σn 2+(T) ≈ 1 × 10−14 cm2, σn +(T) ≈ 1 × 10−14 cm2, and σp 0(T) ≈ 9 × 10−18 cm2 for EH6 and σn 2+(T) ≈ 2 × 10−14 cm2, σn +(T) ≈ 2 × 10−14 cm2, σp 0(T) ≈ 1 × 10−20 cm2 for EH7. Since EH7 has already been identified as a donor transition of the carbon vacancy, we propose that the EH6∕7 center in total represents the overlapping first and second donor transitions of the carbon vacancy defects on both inequivalent lattice sites.

    Ort, förlag, år, upplaga, sidor
    American Institute of Physics (AIP), 2016
    Nyckelord
    4H-SiC, DLTS, MCTS, Carbon vacancy, EH6/7; Z1/2, UT-1, Negative-U, Trap Auger, Deep level
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-121544 (URN)10.1063/1.4954006 (DOI)000379038800035 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF)Vetenskapsrådet
    Anmärkning

    At the time for thesis presentation publication was in status: Manuscript

    Funding agencies: Swedish Foundation for Strategic Research (SSF); Swedish Research Council (VR)

    Tillgänglig från: 2015-09-24 Skapad: 2015-09-24 Senast uppdaterad: 2017-12-01Bibliografiskt granskad
    5. Shallow boron, the deep D-center and their influence on carrier lifetime in n- and p-type 4H-SiC
    Öppna denna publikation i ny flik eller fönster >>Shallow boron, the deep D-center and their influence on carrier lifetime in n- and p-type 4H-SiC
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The shallow boron and deep D-center are analyzed by minority carrier transient spectroscopy (MCTS), deep level transient spectroscopy (DLTS) and optical-electrical MCTS in n-type 4H-SiC with varying concentrations of boron, and in p-type 4H-SiC. MCTS, using high resolution correlation functions, shows the D-center to be composed of two closely overlapping peaks, referred to as D(a) and D(b), both most likely originating from the same defect located on inequivalent lattice sites. The hole capture cross sections of the D center are derived from DLTS filling pulse measurements in p-type material. The electron capture behavior of the D-center is analyzed by optical-electrical MCTS, and we find the center to be a pure hole trap, unable to act as a recombination center, with electron capture cross sections smaller than 1·10-23 cm2. The shallow boron peak is found to be composed of two or more overlapping levels in high resolution MCTS spectra. The shallow levels are further demonstrated to produce minority carrier trapping and detrapping effects in n-type 4H-SiC, which result in long time-resolved photoluminescence (TRPL) transients with microsecond decay constants, even in material containing high concentrations of the lifetime killing center Z1/2.

    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-121545 (URN)
    Tillgänglig från: 2015-09-24 Skapad: 2015-09-24 Senast uppdaterad: 2015-09-24
    6. Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime
    Öppna denna publikation i ny flik eller fönster >>Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime
    Visa övriga...
    2016 (Engelska)Ingår i: Physical Review Applied, ISSN 2331-7019, Vol. 6, nr 1, s. 1-15, artikel-id 014010Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We present a complete analysis of the electron- and hole-capture and -emission processes of the deep levels ON1, ON2a, and ON2b in 4H-SiC and their 6H-SiC counterparts OS1a and OS1b through OS3a and OS3b, which are produced by lifetime enhancement oxidation or implantation and annealing techniques. The modeling is based on a simultaneous numerical fitting of multiple high-resolution capacitance deep-level transient spectroscopy spectra measured with different filling-pulse lengths in n- and p-type material. All defects are found to be double-donor-type positive-U two-level defects with very small hole-capture cross sections, making them recombination centers of low efficiency, in accordance with minority-carrier-lifetime measurements. Their behavior as trapping and weak recombination centers, their large concentrations resulting from the lifetime enhancement oxidations, and their high thermal stability, however, make it advisable to minimize their presence in active regions of devices, for example, the base layer of bipolar junction transistors.

    Ort, förlag, år, upplaga, sidor
    American Physical Society, 2016
    Nyckelord
    Time-resolved photoluminescence, Deep level transient spectroscopy, Minority carrier transient spectroscopy, Lifetime enhancement, Oxidation; Recombination center, 4H-SiC, 6H-SiC
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-121546 (URN)10.1103/PhysRevApplied.6.014010 (DOI)000380125700001 ()
    Forskningsfinansiär
    Stiftelsen för strategisk forskning (SSF)Vetenskapsrådet
    Anmärkning

    At the time for thesis presentation publication was in status: Manuscript

    Tillgänglig från: 2015-09-24 Skapad: 2015-09-24 Senast uppdaterad: 2018-09-01Bibliografiskt granskad
  • 4.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Abdalla, Hassan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Karhu, Robin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime2016Ingår i: Physical Review Applied, ISSN 2331-7019, Vol. 6, nr 1, s. 1-15, artikel-id 014010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a complete analysis of the electron- and hole-capture and -emission processes of the deep levels ON1, ON2a, and ON2b in 4H-SiC and their 6H-SiC counterparts OS1a and OS1b through OS3a and OS3b, which are produced by lifetime enhancement oxidation or implantation and annealing techniques. The modeling is based on a simultaneous numerical fitting of multiple high-resolution capacitance deep-level transient spectroscopy spectra measured with different filling-pulse lengths in n- and p-type material. All defects are found to be double-donor-type positive-U two-level defects with very small hole-capture cross sections, making them recombination centers of low efficiency, in accordance with minority-carrier-lifetime measurements. Their behavior as trapping and weak recombination centers, their large concentrations resulting from the lifetime enhancement oxidations, and their high thermal stability, however, make it advisable to minimize their presence in active regions of devices, for example, the base layer of bipolar junction transistors.

  • 5.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Abdalla, Hassan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska högskolan.
    Lilja, L.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Oxidation induced ON1, ON2a/b defects in 4H-SiC characterized by DLTS2014Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Trans Tech Publications , 2014, Vol. 778-780, s. 281-284Konferensbidrag (Refereegranskat)
    Abstract [en]

    The deep levels ON1 and ON2a/b introduced by oxidation into 4H-SiC are characterized via standard DLTS and via filling pulse dependent DLTS measurements. Separation of the closely spaced ON2a/b defect is achieved by using a higher resolution correlation function (Gaver-Stehfest 4) and apparent energy level, apparent electron capture cross section and filling pulse measurement derived capture cross sections are given.

  • 6.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hallén,, Anders
    Royal Institute of Technology, Sweden.
    Sveinbjörnsson, Einar Ö.
    University of Iceland, Reykjavik, Iceland.
    Kordina, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Comparison of Post-Growth Carrier Lifetime Improvement Methods for 4H-SiC Epilayers2012Ingår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 285-288Konferensbidrag (Refereegranskat)
    Abstract [en]

    We compare two methods for post-growth improvement of bulk carrier lifetime in 4H-SiC: dry oxidations and implantations with either C-12 or N-14, followed by high temperature anneals in Ar atmosphere. Application of these techniques to samples cut from the same wafer/epilayer yields 2- to 11-fold lifetime increases, with the implantation/annealing technive shown to give greater rnaximum lifetimes. The maximum lifetimes reached are similar to 5 mu s after C-12 implantation at 600 degrees C and annealing in Ar for 180 minutes at 1500 degrees C. At higher annealing temperatures the lifetimes decreases, a result which differs from reports in the literature.

  • 7.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    High-Resolution Time-Resolved Carrier Lifetime and Photoluminescence Mapping of 4H-SiC Epilayers2012Ingår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 293-296Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a comparison between time-resolved carrier lifetime mappings of several samples and integrated near band edge intensity photoluminescence mappings using a pulsed laser. High-injection conditions and as-grown material are used, which generally allow for the assumption of a single exponential decay. The photoluminescence intensity under these circumstances is proportional to the carrier lifetime and the mappings can be used to detect lifetime-influencing defects in epilayers and give an estimate of the carrier lifetime variation over the wafer. Several examples for the defect detection capability of the system are given.

  • 8.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Electron and hole capture cross sections of deep levels accessible by DLTS and MCTS in p-type 4H-SiCManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The effective electron (σn(T)) and hole (σn(T)) capture cross sections of the electrically active deep levels HK0, HK2, LB1 and EM1 found in as-grown, high temperature annealed and oxidized p-type 4H-SiC were measured by deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS) and optical-electrical MCTS and DLTS (OE-MCTS and EO-DLTS) in an effort to determine the potential recombination centers in p-type material. Additionally, we also find the D-center, and the deep levels EH6/7, ON1 and ON2 in our samples, while the levels HK1, HK3 and HK4, reported in literature, are always below the detection limit. We further compare deep level concentrations and the timeresolved photoluminescence (TRPL) measured low injection (τLI) in samples annealed at up to 1920 °C. None of the detected deep levels possess σp(T):σn(T) ratios which could enable them to act as efficient recombination centers in the annealed epilayers, where τLI ranges from 1.2·10-6 s to less than 100·10-9 s. However, a clear anti-correlation between τLI and the EH6/7 concentration is found, which is linked to the main lifetime limiting center in n-type material, Z1/2, via their common origin, the carbon vacancy. Due to their large σp(T):σn(T) ratio, the Z1/2 deep levels are not detected by frontside illumination MCTS in p-type material. We thus conclude that the main lifetime limiting deep level(s) in p-type 4HSiC appear to be located in the upper half of the bandgap and are most likely either Z1/2, or other deep levels of intrinsic or partially intrinsic origin with a similar σp(T):σn(T) ratio.

  • 9.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Carrier lifetime in p- and n-type 4H-SiCManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Temperature-dependent time-resolved photoluminescence measurements made in the temperature range from 77 K to 1000 K on free-standing as grown n-type 4H-SiC and p-type 4H-SiC epilayers, which are either as-grown or annealed at 1000 °C, 1400 °C or 1700 °C, are analyzed. The development of the instantaneous carrier lifetime over temperature, calculated from the decay curves of all n- and p-type samples, is found to be identical in the entire temperature range. With increasing annealing temperature only the magnitude of the lifetime in p-type 4H-SiC decreases while the trend remains identical to that in the as-grown n-type sample. Annealing thus only increases the density of the main recombination center which appears to control lifetime in as-grown n- and p-type material. The results implies that the lifetime in all samples may be governed by the same intrinsic defect, which we suggest to be Z1/2.

  • 10.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Son, Nguyen Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC2016Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, nr 23, artikel-id 235703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using medium- and high-resolution multi-spectra fitting of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), optical O-DLTS and optical-electrical (OE)-MCTS measurements, we show that the EH6∕7 deep level in 4H-SiC is composed of two strongly overlapping, two electron emission processes with thermal activation energies of 1.49 eV and 1.58 eV for EH6 and 1.48 eV and 1.66 eV for EH7. The electron emission peaks of EH7 completely overlap while the emission peaks of EH6 occur offset at slightly different temperatures in the spectra. OE-MCTS measurements of the hole capture cross section σp 0(T) in p-type samples reveal a trap-Auger process, whereby hole capture into the defect occupied by two electrons leads to a recombination event and the ejection of the second electron into the conduction band. Values of the hole and electron capture cross sections σn(T) and σp(T) differ strongly due to the donor like nature of the deep levels and while all σn(T) have a negative temperature dependence, the σp(T) appear to be temperature independent. Average values at the DLTS measurement temperature (∼600 K) are σn 2+(T) ≈ 1 × 10−14 cm2, σn +(T) ≈ 1 × 10−14 cm2, and σp 0(T) ≈ 9 × 10−18 cm2 for EH6 and σn 2+(T) ≈ 2 × 10−14 cm2, σn +(T) ≈ 2 × 10−14 cm2, σp 0(T) ≈ 1 × 10−20 cm2 for EH7. Since EH7 has already been identified as a donor transition of the carbon vacancy, we propose that the EH6∕7 center in total represents the overlapping first and second donor transitions of the carbon vacancy defects on both inequivalent lattice sites.

  • 11.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Beyer, Franziska
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karhu, Robin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, J. Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Danielsson, Örjan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kordina, Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC2014Ingår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, nr 8, s. 4104-4110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.

  • 12.
    Booker, Ian Don
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Yazdanfar, Milan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Sveinbjörnsson, Einar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Science Institute, University of Iceland, Reykjavik, Iceland.
    Shallow boron, the deep D-center and their influence on carrier lifetime in n- and p-type 4H-SiCManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The shallow boron and deep D-center are analyzed by minority carrier transient spectroscopy (MCTS), deep level transient spectroscopy (DLTS) and optical-electrical MCTS in n-type 4H-SiC with varying concentrations of boron, and in p-type 4H-SiC. MCTS, using high resolution correlation functions, shows the D-center to be composed of two closely overlapping peaks, referred to as D(a) and D(b), both most likely originating from the same defect located on inequivalent lattice sites. The hole capture cross sections of the D center are derived from DLTS filling pulse measurements in p-type material. The electron capture behavior of the D-center is analyzed by optical-electrical MCTS, and we find the center to be a pure hole trap, unable to act as a recombination center, with electron capture cross sections smaller than 1·10-23 cm2. The shallow boron peak is found to be composed of two or more overlapping levels in high resolution MCTS spectra. The shallow levels are further demonstrated to produce minority carrier trapping and detrapping effects in n-type 4H-SiC, which result in long time-resolved photoluminescence (TRPL) transients with microsecond decay constants, even in material containing high concentrations of the lifetime killing center Z1/2.

  • 13.
    Fagerlind, Martin
    et al.
    Chalmers, Sweden .
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Zirath, Herbert
    Chalmers, Sweden .
    Rorsman, Niklas
    Chalmers, Sweden .
    Influence of Large-Aspect-Ratio Surface Roughness on Electrical Characteristics of AlGaN/AlN/GaN HFETs2012Ingår i: IEEE transactions on device and materials reliability, ISSN 1530-4388, E-ISSN 1558-2574, Vol. 12, nr 3, s. 538-546Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of large-aspect-ratio surface roughness of AlGaN/GaN wafers is investigated. The roughness has a surface morphology consisting of hexagonal peaks with maximum peak-to-valley height of more than 100 nm and lateral peak-to-peak distance between 25 and 100 mu m. Two epitaxial wafers grown at the same time on SiC substrates having different surface orientation and with a resulting difference in AlGaN surface roughness are investigated. Almost no difference is seen in the electrical characteristics of the materials, and the electrical uniformity of the rough material is comparable to that of the smoother material. The reliability of heterostructure field-effect transistors from both materials have been tested by stressing devices for up to 100 h without any significant degradation. No critical effect, from the surface roughness, on device fabrication is experienced, with the exception that the roughness will directly interfere with step-height measurements.

  • 14.
    Hassan, Jawad
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Influence of Growth Mechanism on Carrier Lifetime in on-axis Homoepitaxial Layers of 4H-SiC2012Ingår i: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 157-160Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this report we present homoepitaxial growth of 4H-SiC on Si-face, nominally on-axis substrates with diameters up to 76 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers; local variations in carrier lifetime are different from standard epilayers on off-cut substrates. The properties of the layers were studied with focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneities of surface morphology and different growth mechanisms.

  • 15.
    Kallinger, B.
    et al.
    Fraunhofer IISB, Erlangen, Germany.
    Rommel, M.
    Fraunhofer IISB, Erlangen, Germany.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD2014Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Stafa-Zurich, Switzerland: Trans Tech Publications , 2014, Vol. 778-780, s. 301-304Konferensbidrag (Refereegranskat)
    Abstract [en]

    Carrier lifetime measurements and wafer mappings have been done on several different 4H SiC epiwafers to compare two different measurement techniques, time-resolved photoluminescence and microwave induced photoconductivity decay. The absolute values of the decay time differ by a factor of two, as expected from recombination and measurement theory. Variations within each wafer are comparable with the two techniques. Both techniques are shown to be sensitive to substrate quality and distribution of extended defects.

  • 16.
    Karhu, Robin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Long Charge Carrier Lifetime in As-Grown 4H-SiC Epilayer2016Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 858, s. 125-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Over 150 μm thick epilayers of 4H-SiC with long carrier lifetime have been grown with a chlorinated growth process. The carrier lifetime have been determined by time resolved photoluminescence (TRPL), the lifetime varies a lot between different areas of the sample. This study investigates the origins of lifetime variations in different regions using deep level transient spectroscopy (DLTS), low temperature photoluminescence (LTPL) and a combination of KOH etching and optical microscopy. From optical microscope images it is shown that the area with the shortest carrier lifetime corresponds to an area with high density of structural defects.

  • 17.
    Karhu, Robin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Booking, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ul Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ivanov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    The Role of Chlorine during High Growth Rate Epitaxy2015Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 821-823, s. 141-144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of chlorine has been investigated for high growth rates of 4H-SiC epilayers on 4o off-cut substrates. Samples were grown at a growth rate of approximately 50 and 100 μm/h and various Cl/Si ratios. The growth rate, net doping concentration and charge carrier lifetime have been studied as a function of Cl/Si ratio. This study shows some indications that a high Cl concentration in the growth cell leads to less availability of Si during the growth process.

  • 18.
    Lilja, Louise
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Don Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    The influence of growth conditions on carrier lifetime in 4H-SiC epilayers2013Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 381, s. 43-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    4H-SiC homoepitaxial layers have been grown in a horizontal hot-wall CVD (chemical vapor deposition) reactor and the measured carrier lifetimes have been correlated to the CVD growth conditions. Two different generations of reactors were compared, resulting in measured carrier lifetimes in two different orders of magnitude, from a few hundreds of ns to a few ms. The variations in measured carrier lifetime were correlated to deep level concentrations of the Z(1/2) center and the D-1 center, seen by photoluminescence. Decreasing the growth temperature clearly prolonged the carrier life time and showed lower Z(1/2) concentrations, where as lowering the growth rate only showed a small improvement of the carrier lifetime and no obvious tendencyin Z(1/2) defect concentrations, indicating that Z(1/2) is not the only defect limiting the carrier lifetime. Increasing the C/Si ratio resulted in decreasing Z(1/2) concentrations, indicating the carbon vacancy nature of the defect. However, carrier lifetime measurements showed maximum values for a C/Si ratio of 1 but otherwise an increasing tendency for increasing C/Si ratios. The reactor giving higher carrier lifetimes, correspondingly also showed lower Z(1/2) concentrations indicating the lifetime limiting property of Z(1/2). Furthermore, the D-1 defect intensity increased with growth temperature and decreased with increasing C/Si ratio, similar to the Z(1/2) concentration.

  • 19.
    Lilja, Louise
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Influence of Growth Temperature on Carrier Lifetime in 4H-SiC Epilayers2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Carrier lifetime and formation of defects have been investigated as a function of growth temperature in n-type 4H-SiC epitaxial layers, grown by horizontal hot-wall CVD. Emphasis has been put on having fixed conditions except for the growth temperature, hence growth rate, doping and epilayer thickness were constant in all epilayers independent of growth temperature. An increasing growth temperature gave higher Z1/2 concentrations along with decreasing carrier lifetime. A correlation between growth temperature and D1 defect was also observed.

  • 20.
    Lilja, Louise
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    ul-Hassan, Jawad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian D.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    The Effect of Growth Conditions on Carrier Lifetime in n-type 4H-SiC Epitaxial Layers2012Ingår i: Materials Science Forum Vol 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, s. 161-164Konferensbidrag (Refereegranskat)
    Abstract [en]

    Carrier lifetime has been studied as a function of C/Si ratio and growth rate during epitaxial growth of n-type 4H-SiC using horizontal hot-wall CVD. Effort has been put on keeping all growth parameters constant with the exception of the parameter that is intended to vary. The carrier lifetime is found to decrease with increasing growth rate and the highest carrier lifetime is found for a C/Si ratio of 1. The surface roughness was correlated with epitaxial growth conditions with AFM analysis.

  • 21.
    Sun, Jianwu
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Jokubavicius, Valdas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Gao, L.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Jansson, Mattias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska fakulteten.
    Liu, Xinyu
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Hofmann, J.P.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Hensen, E.J.M.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Linnarsson, M.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Wellmann, P.
    Department of Materials Science 6, University of of Erlangen-Nuremberg, Martensstr. 7, Erlangen, Germany.
    Ramiro, I.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Marti, A.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Syväjärvi, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Solar driven energy conversion applications based on 3C-SiC2016Ingår i: Materials Science Forum, Trans Tech Publications Ltd , 2016, Vol. 858, s. 1028-1031Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a strong and growing worldwide research on exploring renewable energy resources. Solar energy is the most abundant, inexhaustible and clean energy source, but there are profound material challenges to capture, convert and store solar energy. In this work, we explore 3C-SiC as an attractive material towards solar-driven energy conversion applications: (i) Boron doped 3C-SiC as candidate for an intermediate band photovoltaic material, and (ii) 3C-SiC as a photoelectrode for solar-driven water splitting. Absorption spectrum of boron doped 3C-SiC shows a deep energy level at ~0.7 eV above the valence band edge. This indicates that boron doped 3C-SiC may be a good candidate as an intermediate band photovoltaic material, and that bulk like 3C-SiC can have sufficient quality to be a promising electrode for photoelectrochemical water splitting. © 2016 Trans Tech Publications, Switzerland.

  • 22.
    ul Hassan, Jawad
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lilja, Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hallén, Anders
    Lab of Materials and Semiconductor Physics, Royal Institute of Technology P.O. Box Electrum 229, SE-16440 Kista, Sweden.
    Fagerlind, Martin
    Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience (MC2) Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications2013Ingår i: Materials Science Forum (Volumes 740 - 742), Trans Tech Publications Inc., 2013, s. 173-176Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate on-axis homoepitaxial growth of 4H-SiC(0001) PiN structure on 3-inch wafers with 100% 4H polytype in the epilayer excluding the edges. The layers were grown with a thickness of 105 µm and controlled n-type doping of 4 x 1014 cm-3. The epilayers were completely free of basal plane dislocations, in-grown stacking faults and other epitaxial defects, as required for 10 kV high power bipolar devices. Some part of the wafer had a lifetime enhancement procedure to increase lifetime to above 2 µs using carbon implantation. An additional step of epilayer polishing was adapted to reduce surface roughness and implantation damage.

  • 23.
    Widmann, Matthias
    et al.
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Lee, Sang-Yun
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Rendler, Torsten
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Tien Son, Nguyen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Fedder, Helmut
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Paik, Seoyoung
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Yang, Li-Ping
    Beijing Computat Science Research Centre, Peoples R China.
    Zhao, Nan
    Beijing Computat Science Research Centre, Peoples R China.
    Yang, Sen
    University of Stuttgart, Germany.
    Booker, Ian Don
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Denisenko, Andrej
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Jamali, Mohammad
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Ali Momenzadeh, S.
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Gerhardt, Ilja
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Ohshima, Takeshi
    Japan Atom Energy Agency, Japan.
    Gali, Adam
    Hungarian Academic Science, Hungary; Budapest University of Technology and Econ, Hungary.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Wrachtrup, Joerg
    University of Stuttgart, Germany; University of Stuttgart, Germany.
    Coherent control of single spins in silicon carbide at room temperature2015Ingår i: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 14, nr 2, s. 164-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spins in solids are cornerstone elements of quantum spintronics(1). Leading contenders such as defects in diamond(2-5) or individual phosphorus dopants in silicon(6) have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems(5):it has a large bandgap with deep defects(7-9) and benefits from mature fabrication techniques(10-12). Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology.

  • 24.
    Yazdanfar, Milan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Don Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gueorguiev Ivanov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kordina, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Process stability and morphology optimization of very thick 4H-SiC epitaxial layers grown by chloride-based CVD2013Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 380, s. 55-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of a chemical vapor deposition (CVD) process for very thick silicon carbide (SiC) epitaxial layers suitable for high power devices is demonstrated by epitaxial growth of 200 nm thick, low doped 4H-SiC layers with excellent morphology at growth rates exceeding 100 nm/h. The process development was done in a hot wall CVD reactor without rotation using both SiCl4 and SiH4+HCl precursor approaches to chloride based growth chemistry. A C/Si ratio andlt;1 and an optimized in-situ etch are shown to be the key parameters to achieve 200 nm thick, low doped epitaxial layers with excellent morphology.

  • 25.
    Yazdanfar, Milan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Stenberg, Pontus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Don Booker, Ian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gueorguiev Ivanov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska högskolan.
    Kordina, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Morphology optimization of very thick 4H-SiC epitaxial layers2013Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2012, Trans Tech Publications , 2013, Vol. 740-742, s. 251-254Konferensbidrag (Refereegranskat)
    Abstract [en]

    Epitaxial growth of about 200 gm thick, low doped 4H-SiC layers grown on n-type 8 degrees off-axis Si-face substrates at growth rates around 100 mu m/h has been done in order to realize thick epitaxial layers with excellent morphology suitable for high power devices. The study was done in a hot wall chemical vapor deposition reactor without rotation. The growth of such thick layers required favorable pre-growth conditions and in-situ etch. The growth of 190 gm thick, low doped epitaxial layers with excellent morphology was possible when the C/Si ratio was below 0.9. A low C/Si ratio and a favorable in-situ etch are shown to be the key parameters to achieve 190 gm thick epitaxial layers with excellent morphology.

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