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Lilja, Louise
Publications (10 of 12) Show all publications
Booker, I. D., Abdalla, H., Hassan, J., Karhu, R., Lilja, L., Janzén, E. & Sveinbjörnsson, E. (2016). Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime. Physical Review Applied, 6(1), 1-15, Article ID 014010.
Open this publication in new window or tab >>Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime
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2016 (English)In: Physical Review Applied, ISSN 2331-7019, Vol. 6, no 1, p. 1-15, article id 014010Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
American Physical Society, 2016
Keyword
Time-resolved photoluminescence, Deep level transient spectroscopy, Minority carrier transient spectroscopy, Lifetime enhancement, Oxidation; Recombination center, 4H-SiC, 6H-SiC
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-121546 (URN)10.1103/PhysRevApplied.6.014010 (DOI)000380125700001 ()
Funder
Swedish Foundation for Strategic Research Swedish Research Council
Note

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

Available from: 2015-09-24 Created: 2015-09-24 Last updated: 2016-08-22Bibliographically approved
Lilja, L., Ul-Hassan, J., Janzén, E. & Bergman, P. (2015). In-grown stacking-faults in 4H-SiC epilayers grown on 2 degrees off-cut substrates. Physica status solidi. B, Basic research, 252(6), 1319-1324
Open this publication in new window or tab >>In-grown stacking-faults in 4H-SiC epilayers grown on 2 degrees off-cut substrates
2015 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 252, no 6, p. 1319-1324Article in journal (Refereed) Published
Abstract [en]

4H-SiC epilayers were grown on 2 degrees off-cut substrates using standard silane/propane chemistry, with the aim of characterizing in-grown stacking faults. The stacking faults were analyzed with low temperature photoluminescence spectroscopy, room temperature photoluminescence mappings, room temperature cathodoluminescence and synchrotron white beam X-ray topography. At least three different types of in-grown stacking faults were observed, including double Shockley stacking faults, triple Shockley stacking faults and bar-shaped stacking faults. Those stacking faults are all previously found in 4 degrees and 8 degrees off-cut epilayers; however, the geometrical size is larger in epilayers grown on 2 degrees off-cut substrates due to lower off-cut angle. The stacking faults were formed close to the epilayer/substrate interface during the epitaxial growth. (C) 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2015
Keyword
chemical vapor deposition; epitaxy; photoluminescence; SiC; stacking faults
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-120065 (URN)10.1002/pssb.201451710 (DOI)000355756200018 ()
Note

Funding Agencies|Swedish Research Council (VR); Advanced Functional Materials (AFM); Swedish Foundation for Strategic Research (SSF)

Available from: 2015-07-06 Created: 2015-07-06 Last updated: 2017-12-04
Han, G., Mueller, W. E. G., Wang, X., Lilja, L. & Shen, Z. (2015). Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization. Materials science & engineering. C, biomimetic materials, sensors and systems, 47, 376-383
Open this publication in new window or tab >>Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization
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2015 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 47, p. 376-383Article in journal (Refereed) Published
Abstract [en]

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 gm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Porosity; Titanium oxide; Cell adhesion; Cell proliferation; Surface topography
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-114233 (URN)10.1016/j.msec.2014.11.021 (DOI)000347581600045 ()25492210 (PubMedID)
Note

Funding Agencies|European Commission [604036, 215507, 286059, 266033, 268476, 311848]; Knut and Alice Wallenberg foundation; ERC Advanced Investigator Grant [268476]; Deutsche Forschungsgemeinschaft [Schr 277/10-2]; International Human Frontier Science Program; Public Welfare Project of Ministry of Land and Resources of the Peoples Republic of China [201011005-06]; International Science and Technology Cooperation Program of China [2008DFA00980]

Available from: 2015-02-16 Created: 2015-02-16 Last updated: 2017-12-04
Booker, I. D., Ul Hassan, J., Lilja, L., Beyer, F., Karhu, R., Bergman, J. P., . . . Janzén, E. (2014). Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC. Crystal Growth & Design, 14(8), 4104-4110
Open this publication in new window or tab >>Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC
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2014 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 8, p. 4104-4110Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2014
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-110278 (URN)10.1021/cg5007154 (DOI)000340080400049 ()
Note

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

Available from: 2014-09-05 Created: 2014-09-05 Last updated: 2017-12-05Bibliographically approved
Kallinger, B., Rommel, M., Lilja, L., ul-Hassan, J., Booker, I. D., Janzén, E. & Bergman, P. (2014). Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD. In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2: . Paper presented at 15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013 (pp. 301-304). Stafa-Zurich, Switzerland: Trans Tech Publications, 778-780
Open this publication in new window or tab >>Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD
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2014 (English)In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Stafa-Zurich, Switzerland: Trans Tech Publications , 2014, Vol. 778-780, p. 301-304Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Stafa-Zurich, Switzerland: Trans Tech Publications, 2014
Series
Materials Science Forum, ISSN 0255-5476 ; vol 778-780
Keyword
Carrier lifetime; Photoluminescence; Silicon carbide; μ-PCD
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-110541 (URN)10.4028/www.scientific.net/MSF.778-780.301 (DOI)000336634100071 ()2-s2.0-84896069395 (Scopus ID)9783038350101 (ISBN)
Conference
15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013
Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2014-09-15
Ul-Hassan, J., Bae, H., Lilja, L., Farkas, I., Kim, I., Stenberg, P., . . . Janzén, E. (2014). Fast growth rate epitaxy on 4((degrees)under-bar) off-cut 4-inch diameter 4H-SiC wafers. In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2: . Paper presented at 15th International Conference on Silicon Carbide and Related Materials (ICSCRM), Miyazaki, Japan, 29 Sptember - 4 October 2013 (pp. 179-182). Trans Tech Publications, 778-780
Open this publication in new window or tab >>Fast growth rate epitaxy on 4((degrees)under-bar) off-cut 4-inch diameter 4H-SiC wafers
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2014 (English)In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Trans Tech Publications , 2014, Vol. 778-780, p. 179-182Conference paper, Published paper (Refereed)
Abstract [en]

We report the development of over 100 mu m/h growth rate process on 4-inch diameter wafers using chlorinated growth. The optimized growth process has shown extremely smooth epilayers completely free of surface step-bunching with very low surface defect density, high uniformity in thickness and doping and high run to run reproducibility in growth rate, controlled doping and defect density.

Place, publisher, year, edition, pages
Trans Tech Publications, 2014
Series
Materials Science Forum, ISSN 1662-9752 ; 778-780
Keyword
Fast epitaxial growth; high growth rate; chlorinated growth; atomic force microscopy
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-108193 (URN)10.4028/www.scientific.net/MSF.778-780.179 (DOI)000336634100042 ()
Conference
15th International Conference on Silicon Carbide and Related Materials (ICSCRM), Miyazaki, Japan, 29 Sptember - 4 October 2013
Available from: 2014-06-26 Created: 2014-06-26 Last updated: 2016-06-02Bibliographically approved
Lilja, L., ul-Hassan, J., Booker, I., Bergman, P. & Janzén, E. (2013). Influence of Growth Temperature on Carrier Lifetime in 4H-SiC Epilayers. In: : . Paper presented at 9th European Conference on Silicon Carbide and Related Materials (ECSCRM 2012), 2-6 September 2012, St Petersburg, Russia (pp. 637-640). Trans Tech Publications Inc., 740-742
Open this publication in new window or tab >>Influence of Growth Temperature on Carrier Lifetime in 4H-SiC Epilayers
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2013 (English)Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2013
Keyword
Atomic Force Microscopy, Carrier Lifetime, DLTS, Epitaxial Growth, Horizontal Hot-Wall CVD, Intrinsic Defect, Photoluminescence (PL)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-88341 (URN)10.4028/www.scientific.net/MSF.740-742.637 (DOI)000319785500151 ()
Conference
9th European Conference on Silicon Carbide and Related Materials (ECSCRM 2012), 2-6 September 2012, St Petersburg, Russia
Available from: 2013-02-04 Created: 2013-02-04 Last updated: 2014-10-20
ul Hassan, J., Booker, I., Lilja, L., Hallén, A., Fagerlind, M., Bergman, P. & Janzén, E. (2013). On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications. In: Materials Science Forum (Volumes 740 - 742): . Paper presented at 9th European Conference on Silicon Carbide and Related Materials (ECSCRM 2012) (pp. 173-176). Trans Tech Publications Inc.
Open this publication in new window or tab >>On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications
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2013 (English)In: Materials Science Forum (Volumes 740 - 742), Trans Tech Publications Inc., 2013, p. 173-176Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2013
Keyword
Carrier Lifetime, Chemical Vapor Deposition (CVD), Growth Mechanism, High Power Devices, On-Axis
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-91406 (URN)10.4028/www.scientific.net/MSF.740-742.173 (DOI)000319785500041 ()
Conference
9th European Conference on Silicon Carbide and Related Materials (ECSCRM 2012)
Available from: 2013-04-24 Created: 2013-04-24 Last updated: 2013-08-23
Lilja, L., Don Booker, I., ul-Hassan, J., Janzén, E. & Bergman, P. (2013). The influence of growth conditions on carrier lifetime in 4H-SiC epilayers. Journal of Crystal Growth, 381, 43-50
Open this publication in new window or tab >>The influence of growth conditions on carrier lifetime in 4H-SiC epilayers
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2013 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 381, p. 43-50Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Atomic force microscopy, Characterization, Chemical vapor deposition processes, Hot-wall epitaxy, Semiconducting materials, Bipolar transistors
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-98658 (URN)10.1016/j.jcrysgro.2013.06.037 (DOI)000324303500009 ()
Note

Funding Agencies|Swedish Research Council (VR)||Advanced Functional Materials (AFM)||Swedish Foundation for Strategic Research (SSF)||

Available from: 2013-10-10 Created: 2013-10-10 Last updated: 2017-12-06
Hassan, J., Lilja, L., Booker, I. D., Bergman, P. & Janzén, E. (2012). Influence of Growth Mechanism on Carrier Lifetime in on-axis Homoepitaxial Layers of 4H-SiC. In: Materials Science Forum Vols 717 - 720. Paper presented at 14th International Conference on Silicon Carbide and Related Materials (ICSCRM 2011), 11-16 September 2011, Cleveland, OH, USA (pp. 157-160). Trans Tech Publications Inc., 717-720
Open this publication in new window or tab >>Influence of Growth Mechanism on Carrier Lifetime in on-axis Homoepitaxial Layers of 4H-SiC
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2012 (English)In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, p. 157-160Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2012
Keyword
on-axis; chemical vapor deposition; growth mechanism; carrier lifetime
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87567 (URN)10.4028/www.scientific.net/MSF.717-720.157 (DOI)000309431000037 ()
Conference
14th International Conference on Silicon Carbide and Related Materials (ICSCRM 2011), 11-16 September 2011, Cleveland, OH, USA
Available from: 2013-01-18 Created: 2013-01-18 Last updated: 2013-02-04
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