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Kordina, Olle
Alternative names
Publications (10 of 59) Show all publications
Duc Tran, T., Pozina, G., Nguyen, T. S., Kordina, O., Janzén, E., Ohshima, T. & Hemmingsson, C. (2016). Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy. Journal of Applied Physics, 119(9)
Open this publication in new window or tab >>Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy
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2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 9Article in journal (Refereed) Published
Abstract [en]

By minority carrier transient spectroscopy on as-grown n-type bulk GaN produced by halide vapor phase epitaxy (HVPE) one hole trap labelled H1 (EV + 0.34 eV) has been detected. After 2 MeV-energy electron irradiation, the concentration of H1 increases and at fluences higher than 5×1014 cm-2, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (EC - 0.12 eV) and T2 (EC - 0.23 eV) increases. By studying the increase of the concentration versus electron irradiation fluences, the introduction rate of T1 and T2 using 2 MeV-energy electrons was determined to 7X10-3 cm-1 and 0.9 cm-1, respectively. Due to the low introduction rate of T1 and the low threading dislocation density in the HVPE bulk GaN material, it is suggested that the defect is associated with a primary defect decorating extended structural defects. The high introduction rate of the trap H1 suggests that the H1 defect is associated with a primary intrinsic defect or a complex.

Keywords
Deep level, GaN, DLTS, irradiation
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-121709 (URN)10.1063/1.4943029 (DOI)000372351900075 ()
Note

Funding agencies:  Swedish Research Council (VR); Swedish Energy Agency

Vid tiden för disputation förelåg publikationen som manuskript

Available from: 2015-10-02 Created: 2015-10-02 Last updated: 2017-12-01Bibliographically approved
Sukkaew, P., Ojamäe, L., Kordina, O., Janzén, E. & Danielsson, Ö. (2016). Thermochemical Properties of Halides and Halohydrides of Silicon and Carbon. ECS Journal of Solid State Science and Technology, 5(2), P27-P35
Open this publication in new window or tab >>Thermochemical Properties of Halides and Halohydrides of Silicon and Carbon
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2016 (English)In: ECS Journal of Solid State Science and Technology, ISSN 2162-8769, E-ISSN 2162-8777, Vol. 5, no 2, p. P27-P35Article in journal (Refereed) Published
Abstract [en]

Atomization energies, enthalpies of formation, entropies as well as heat capacities of the SiHnXm and CHnXm systems, with X being F, Cl and Br, have been studied using quantum chemical calculations. The Gaussian-4 theory (G4) and Weizman-1 theory as modified by Barnes et al. 2009 (W1RO) have been applied in the calculations of the electronic, zero point and thermal energies. The effects of low-lying electronically excited states due to spin orbit coupling were included for all atoms and diatomic species by mean of the electronic partition functions derived from the experimental or computational energy splittings. The atomization energies, enthalpies of formation, entropies and heat capacities derived from both methods were observed to be reliable. The thermochemical properties in the temperature range of 298-2500 K are provided in the form of 7-coefficient NASA polynomials. (C) The Author(s) 2015. Published by ECS. All rights reserved.

Place, publisher, year, edition, pages
ELECTROCHEMICAL SOC INC, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-124117 (URN)10.1149/2.0081602jss (DOI)000365748800023 ()
Note

Funding Agencies|Swedish Foundation for Strategic Research

Available from: 2016-01-22 Created: 2016-01-19 Last updated: 2017-11-30
Yazdanfar, M., Kalered, E., Danielsson, Ö., Kordina, O., Nilsson, D., Ivanov, I. G., . . . Pedersen, H. (2015). Brominated chemistry for chemical vapor deposition of electronic grade SiC. Chemistry of Materials, 27(3), 793-801
Open this publication in new window or tab >>Brominated chemistry for chemical vapor deposition of electronic grade SiC
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2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 3, p. 793-801Article in journal (Refereed) Published
Abstract [en]

Chlorinated chemical vapor deposition (CVD) chemistry for growth of homoepitaxial layers of silicon carbide (SiC) has paved the way for very thick epitaxial layers in short deposition time as well as novel crystal growth processes for SiC. Here, we explore the possibility to also use a brominated chemistry for SiC CVD by using HBr as additive to the standard SiC CVD precursors. We find that brominated chemistry leads to the same high material quality and control of material properties during deposition as chlorinated chemistry and that the growth rate is on average 10 % higher for a brominated chemistry compared to chlorinated chemistry. Brominated and chlorinated SiC CVD also show very similar gas phase chemistries in thermochemical modelling. This study thus argues that brominated chemistry is a strong alternative for SiC CVD since the deposition rate can be increased with preserved material quality. The thermochemical modelling also suggest that the currently used chemical mechanism for halogenated SiC CVD might need to be revised.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-111075 (URN)10.1021/acs.chemmater.5b00074 (DOI)000349934500016 ()
Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2018-06-19Bibliographically approved
Gällström, A., Magnusson, B., Leone, S., Kordina, O., Son, N. T., Ivády, V., . . . Ivanov, I. G. (2015). Optical properties and Zeeman spectroscopy of niobium in silicon carbide. Physical Review B. Condensed Matter and Materials Physics, 92(7), 1-14, Article ID 075207.
Open this publication in new window or tab >>Optical properties and Zeeman spectroscopy of niobium in silicon carbide
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2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 7, p. 1-14, article id 075207Article in journal (Refereed) Published
Abstract [en]

The optical signature of niobium in the low-temperature photoluminescence spectra of three common polytypes of SiC (4H, 6H, and 15R) is observed and confirms the previously suggested concept that Nb occupies preferably the Si-C divacancy with both Si and C at hexagonal sites. Using this concept we propose a model considering a Nb-bound exciton, the recombination of which is responsible for the observed luminescence. The exciton energy is estimated using first-principles calculation and the result is in very good agreement with the experimentally observed photon energy in 4H SiC at low temperature. The appearance of six Nb-related lines in the spectra of the hexagonal 4H and 6H polytypes at higher temperatures is tentatively explained on the grounds of the proposed model and the concept that the Nb center can exist in both C1h and C3v symmetries. The Zeeman splitting of the photoluminescence lines is also recorded in two different experimental geometries and the results are compared with theory based on phenomenological Hamiltonians. Our results show that Nb occupying the divacancy at the hexagonal site in the studied SiC polytypes behaves like a deep acceptor.

Place, publisher, year, edition, pages
American Physical Society, 2015
National Category
Theoretical Chemistry Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-117972 (URN)10.1103/PhysRevB.92.075207 (DOI)000362204100001 ()
Note

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

Funding Agencies|Knut and Alice Wallenberg Foundation; Lendulet program of the Hungarian Academy of Sciences; Hungarian OTKA Project [K101819]; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Tomsk State University Academic D. I. Mendeleev Fund Program [8.1.18.2015]

Available from: 2015-05-19 Created: 2015-05-19 Last updated: 2017-12-04Bibliographically approved
Duc Tran, T., Pozina, G., Nguyen, T. S., Janzén, E., Kordina, O., Ohshima, T. & Hemmingsson, C. (2015). Thermal behavior of irradiation-induced-deep levels in bulk GaN.
Open this publication in new window or tab >>Thermal behavior of irradiation-induced-deep levels in bulk GaN
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2015 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Bulk GaN grown by halide vapor phase epitaxy and irradiated by 2 MeV electrons at a fluence of 5×1016 cm-2 were studied by deep level transient spectroscopy. After irradiation, two new peaks labelled D0 (EC – 0.18 eV) and D1 (EC – 0.13 eV) are observed. From isochronal annealing studies in the temperature range of 350 - 600 K, it is observed that peak D0 is completely annealed out already at 550 K while the broad peak D1 has a more complex annealing behavior. The concentration of D1 is decreasing during annealing and its peak position is shifted to higher temperatures, until a relatively stable peak labelled D2 (EC – 0.24 eV) is formed. From an isothermal annealing study of D2, it is concluded that the annealing process can be described by a first order annealing process with an activation energy and prefactor of 1.2 eV and 6.6 × 105 s-1, respectively. From the large pre-factor it is concluded that the annihilation of D2 is governed by a long-range migration process. From its annealing behavior, it is suggested that trap D2 may be related to the VGa.

Keywords
Deep level, GaN, DLTS, irradiation
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-121708 (URN)
Available from: 2015-10-02 Created: 2015-10-02 Last updated: 2015-10-02Bibliographically approved
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
Yazdanfar, M., Pedersen, H., Kordina, O. & Janzén, E. (2014). Effect of process parameters on dislocation density in thick 4H-SiC epitaxial layers grown by chloride-based CVD on 4 degrees off-axis substrates. In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2: . Paper presented at The International Conference on Silicon Carbide and Related Materials, September 29-October 4, 2013, Phoenix Seagaia Resort, Miyazaki, Japan (pp. 159-162). Trans Tech Publications, 778-780
Open this publication in new window or tab >>Effect of process parameters on dislocation density in thick 4H-SiC epitaxial layers grown by chloride-based CVD on 4 degrees off-axis substrates
2014 (English)In: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, Trans Tech Publications , 2014, Vol. 778-780, p. 159-162Conference paper, Published paper (Refereed)
Abstract [en]

The effect of process parameters such as growth temperature, C/Si ratio, etching time, and Si/H2 ratio on dislocation density was investigated by performing KOH etching on 100 mu m thick epitaxial layers grown on 4 degrees off axis 4H-SiC substrates at various growth conditions by a chemical vapor deposition (CVD) process using a chloride-based chemistry to achieve growth rates exceeding 100 mu m/h. We observe that the growth temperature and the growth rate have no significant influence on the dislocation density in the grown epitaxial layers. A low C/Si ratio increases the density of threading screw dislocations (TSD) markedly. The basal plane dislocation (BPD) density was reduced by using a proper in-situ etch prior to growth.

Place, publisher, year, edition, pages
Trans Tech Publications, 2014
Series
Materials Science Forum, ISSN 1662-9752 ; 778-780
Keywords
Silicon Carbide; SiC; CVD; Dislocation; 4 degrees off-axis substrates; Epitaxial layers
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-108191 (URN)10.4028/www.scientific.net/MSF.778-780.159 (DOI)000336634100037 ()
Conference
The International Conference on Silicon Carbide and Related Materials, September 29-October 4, 2013, Phoenix Seagaia Resort, Miyazaki, Japan
Available from: 2014-06-26 Created: 2014-06-26 Last updated: 2015-03-11
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
Keywords
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
Yazdanfar, M., Danielsson, Ö., Kordina, O., Janzén, E. & Pedersen, H. (2014). Finding the Optimum Chloride-Based Chemistry for Chemical Vapor Deposition of SiC. ECS Journal of Solid State Science and Technology, 3(10), P320-P323
Open this publication in new window or tab >>Finding the Optimum Chloride-Based Chemistry for Chemical Vapor Deposition of SiC
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2014 (English)In: ECS Journal of Solid State Science and Technology, ISSN 2162-8769, E-ISSN 2162-8777, Vol. 3, no 10, p. P320-P323Article in journal (Refereed) Published
Abstract [en]

Chemical vapor deposition of silicon carbide with a chloride-based chemistry can be done using several different silicon and carbon precursors. Here, we present a comparative study of SiCl4, SiHCl3, SiH4+HCl, C3H8, C2H4 and CH4 in an attempt to find the optimal precursor combination. We find that while the chlorinated silanes SiCl4 and especially SiHCl3 give higher growth rate than natural silane and HCl, SiH4+HCl gives better morphology at C/Si around 1 and SiCl4 gives the best morphology at low C/Si. Our study shows no effect on doping incorporation with precursor chemistry. We suggest that these results can be explained by the number of reaction steps in the gas phase chemical reaction mechanisms for producing SiCl2, which is the most important Si species, and by formation of organosilicons in the gas phase. As carbon precursor, C3H8 or C2H4 are more or less equal in performance with a slight advantage for C3H8, CH4 is however not a carbon precursor that should be used unless extraordinary growth conditions are needed.

Place, publisher, year, edition, pages
ECS, 2014
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-111074 (URN)10.1149/2.0111410jss (DOI)000341962100011 ()
Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2017-12-05Bibliographically approved
Ivanov, I. G., Yazdanfar, M., Lundqvist, B., Chen, J.-T., ul-Hassan, J., Stenberg, P., . . . Janzén, E. (2014). High-Resolution Raman and Luminescence Spectroscopy of Isotope-Pure (SiC)-Si-28-C-12, Natural and C-13 - Enriched 4H-SIC. 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), 29 September - 4 October 2013, Miyazaki, Japan (pp. 471-474). Trans Tech Publications Inc., 778-780
Open this publication in new window or tab >>High-Resolution Raman and Luminescence Spectroscopy of Isotope-Pure (SiC)-Si-28-C-12, Natural and C-13 - Enriched 4H-SIC
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2014 (English)In: Silicon Carbide and Related Materials 2013, PTS 1 AND 2, Trans Tech Publications Inc., 2014, Vol. 778-780, p. 471-474Conference paper, Published paper (Refereed)
Abstract [en]

The optical properties of isotope-pure (SiC)-Si-28-C-12, natural SiC and enriched with C-13 isotope samples of the 4H polytype are studied by means of Raman and photoluminescence spectroscopies. The phonon energies of the Raman active phonons at the Gamma point and the phonons at the M point of the Brillouin zone are experimentally determined. The excitonic bandgaps of the samples are accurately derived using tunable laser excitation and the phonon energies obtained from the photoluminescence spectra. Qualitative comparison with previously reported results on isotope-controlled Si is presented.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
Series
Materials Science Forum, ISSN 1662-9752 ; 778-780
Keywords
isotope-pure SiC; isotope-enriched SiC; Raman spectroscopy; photoluminescence; bandgap variation with isotope content
National Category
Ceramics
Identifiers
urn:nbn:se:liu:diva-108198 (URN)10.4028/www.scientific.net/MSF.778-780.471 (DOI)000336634100110 ()
Conference
15th International Conference on Silicon Carbide and Related Materials (ICSCRM 2013), 29 September - 4 October 2013, Miyazaki, Japan
Available from: 2014-06-26 Created: 2014-06-26 Last updated: 2014-10-28Bibliographically approved
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