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Marx, G., Engelbrecht, J. A., Lee, M. E., Wagener, M. C. & Henry, A. (2016). Comments on a peak of AlxGa1-xN observed by infrared reflectance. Infrared physics & technology, 76, 493-499
Open this publication in new window or tab >>Comments on a peak of AlxGa1-xN observed by infrared reflectance
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2016 (English)In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 76, p. 493-499Article in journal (Refereed) Published
Abstract [en]

AlxGa1-xN epilayers, grown on c-plane oriented sapphire substrates by metal organic chemical vapour deposition (MOCVD), were evaluated using FTIR infrared reflectance spectroscopy. A peak at similar to 850 cm(-1) in the reflectance spectra, not reported before, was observed. Possible origins for this peak are considered and discussed. (C) 2016 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2016
Keywords
AlxGa1-xN; Infrared reflectance; Unassigned peak origin
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-130141 (URN)10.1016/j.infrared.2016.03.024 (DOI)000377725100059 ()
Note

Funding Agencies|National Research Foundation, South Africa

Available from: 2016-07-12 Created: 2016-07-11 Last updated: 2017-11-28
Henry, A., Chubarov, M., Czigany, Z., Garbrecht, M. & Högberg, H. (2016). Early stages of growth and crystal structure evolution of boron nitride thin films. Paper presented at 6th International Symposium on Growth of III-Nitrides (ISGN). Japanese Journal of Applied Physics, 55(5), 05FD06
Open this publication in new window or tab >>Early stages of growth and crystal structure evolution of boron nitride thin films
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2016 (English)In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, no 5, p. 05FD06-Article in journal (Refereed) Published
Abstract [en]

A study of the nucleation and crystal structure evolution at the early stages of the growth of sp(2)-BN thin films on 6H-SiC and alpha-Al2O3 substrates is presented. The growth is performed at low pressure and high temperature in a hot wall CVD reactor, using ammonia and triethylboron as precursors, and H-2 as carrier gas. From high-resolution transmission electron microscopy and X-ray thin film diffraction measurements we observe that polytype pure rhombohedral BN (r-BN) is obtained on 6H-SiC substrates. On alpha-Al2O3 an AlN buffer obtained by nitridation is needed to promote the growth of hexagonal BN (h-BN) to a thickness of around 4 nm followed by a transition to r-BN growth. In addition, when r-BN is obtained, triangular features show up in plan-view scanning electron microscopy which are not seen on thin h-BN layers. The formation of BN after already one minute of growth is confirmed by X-ray photoelectron spectroscopy. (C) 2016 The Japan Society of Applied Physics

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-128949 (URN)10.7567/JJAP.55.05FD06 (DOI)000374697600030 ()
Conference
6th International Symposium on Growth of III-Nitrides (ISGN)
Available from: 2016-06-09 Created: 2016-06-07 Last updated: 2018-03-23
Hatayama, T., Henry, A., Yano, H. & Fuyuki, T. (2016). Low-temperature photoluminescence of 8H-SiC homoepitaxial layer. Japanese Journal of Applied Physics, 55(2), 020303
Open this publication in new window or tab >>Low-temperature photoluminescence of 8H-SiC homoepitaxial layer
2016 (English)In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, no 2, p. 020303-Article in journal (Refereed) Published
Abstract [en]

Low-temperature photoluminescence of a nitrogen-doped 8H-SiC epilayer homoepitaxially grown by a chemical vapor deposition method is reported. The polytype and stacking sequence of the epilayers were confirmed by transmission electron microscopy analyses. The identification of emission lines is discussed in terms of the temperature dependence of the luminescence spectra. Luminescence related to the free excitons and the nitrogen-bound excitons is observed, which allows the determination of the excitonic bandgap of the 8H-SiC polytype. In addition, the low binding energies found for the nitrogen-bound excitons imply shallow levels for the nitrogen donors. (C) 2016 The Japan Society of Applied Physics

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-125306 (URN)10.7567/JJAP.55.020303 (DOI)000369005300003 ()
Available from: 2016-02-24 Created: 2016-02-19 Last updated: 2017-11-30
Chubarov, M., Pedersen, H., Högberg, H., Henry, A. & Czigany, Z. (2015). Initial stages of growth and the influence of temperature during chemical vapor deposition of sp(2)-BN films. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 33(6), 061520
Open this publication in new window or tab >>Initial stages of growth and the influence of temperature during chemical vapor deposition of sp(2)-BN films
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2015 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 33, no 6, p. 061520-Article in journal (Refereed) Published
Abstract [en]

Knowledge of the structural evolution of thin films, starting by the initial stages of growth, is important to control the quality and properties of the film. The authors present a study on the initial stages of growth and the temperature influence on the structural evolution of sp(2) hybridized boron nitride (BN) thin films during chemical vapor deposition (CVD) with triethyl boron and ammonia as precursors. Nucleation of hexagonal BN (h-BN) occurs at 1200 degrees C on alpha-Al2O3 with an AlN buffer layer (AlN/alpha-Al2O3). At 1500 degrees C, h-BN grows with a layer-by-layer growth mode on AlN/alpha-Al2O3 up to similar to 4 nm after which the film structure changes to rhombohedral BN (r-BN). Then, r-BN growth proceeds with a mixed layer-by-layer and island growth mode. h-BN does not grow on 6H-SiC substrates; instead, r-BN nucleates and grows directly with a mixed layer-by-layer and island growth mode. These differences may be caused by differences in substrate surface temperature due to different thermal conductivities of the substrate materials. These results add to the understanding of the growth process of sp(2)-BN employing CVD. (C) 2015 American Vacuum Society.

Place, publisher, year, edition, pages
A V S AMER INST PHYSICS, 2015
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123831 (URN)10.1116/1.4935155 (DOI)000365503800054 ()
Note

Funding Agencies|Swedish Research Council (VR) [621-2013-5585]; Carl Tryggers Stiftelse [12:175]; CeNano Program at Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; Bolyai Janos research scholarship of Hungarian Academy of Sciences

Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2017-12-01
Engelbrecht, J. A., van Rooyen, I. J., Henry, A., Janzén, E. & Sephton, B. (2015). Notes on the plasma resonance peak employed to determine doping in SiC. Infrared physics & technology, 72, 95-100
Open this publication in new window or tab >>Notes on the plasma resonance peak employed to determine doping in SiC
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2015 (English)In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 72, p. 95-100Article in journal (Refereed) Published
Abstract [en]

The doping level of a semiconductor material can be determined using the plasma resonance frequency to obtain the carrier concentration associated with doping. This paper provides an overview of the procedure for the three most common polytypes of SiC. Results for 3C-SiC are presented and discussed. In phosphorus doped samples analysed, it is submitted that the 2nd plasma resonance cannot be detected due to high values of the free carrier damping constant gamma. (C) 2015 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2015
Keywords
Infrared reflectance; SiC; Plasma resonance; Doping concentration
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-122214 (URN)10.1016/j.infrared.2015.07.007 (DOI)000362146700012 ()
Note

Funding Agencies|National Research Foundation (NRF), South Africa

Available from: 2015-10-26 Created: 2015-10-23 Last updated: 2017-12-01
Chubarov, M., Pedersen, H., Högberg, H., Czigany, Z., Garbrecht, M. & Henry, A. (2015). Polytype pure sp2-BN thin films as dictated by the substrate crystal structure. Chemistry of Materials, 27(5), 1640-1645
Open this publication in new window or tab >>Polytype pure sp2-BN thin films as dictated by the substrate crystal structure
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2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 5, p. 1640-1645Article in journal (Refereed) Published
Abstract [en]

Boron nitride (BN) is a promising semiconductor material, but its current exploration is hampered by difficulties in growth of single crystalline phase-pure thin films. We compare the growth of sp2-BN by chemical vapor deposition on (0001) 6H-SiC and on (0001) α-Al2O3 substrates with an AlN buffer layer. Polytype-pure rhombohedral BN (r-BN) with a thickness of 200 nm is observed on SiC whereas hexagonal BN (h-BN) nucleates and grows on the AlN buffer layer. For the latter case after a thickness of 4 nm, the h-BN growth is followed by r-BN growth to a total thickness of 200 nm. We find that the polytype of the sp2-BN films is determined by the ordering of Si-C or Al-N atomic pairs in the underlying crystalline structure (SiC or AlN). In the latter case the change from h-BN to r-BN is triggered by stress relaxation. This is important for the development of BN semiconductor device technology.

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112577 (URN)10.1021/cm5043815 (DOI)000350919000025 ()
Note

This work was supported by the Swedish Research Council (VR, Grant 621-2013-5585), Carl Tryggers Foundation (No. 12:175), and the CeNano program at Linkoping University. H.H. acknowledges support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU No. 2009-00971). Z.C. acknowledges the support of the Bolyai Janos research scholarship of the Hungarian Academy of Sciences. The Knut and Alice Wallenberg (KAW) Foundation is acknowledged for the Electron Microscope Laboratory in Linkoping. Sven G. Andersson is gratefully acknowledged for his technical support of the growth activities.

Available from: 2014-12-04 Created: 2014-12-04 Last updated: 2017-12-05Bibliographically approved
Thierry-Jebali, N., Lazar, M., Vo-Ha, A., Carole, D., Souliere, V., Henry, A., . . . Brosselard, P. (2014). Applications of vapor-liquid-solid selective epitaxy of highly p-type doped 4H-SiC: PiN diodes with peripheral protection and improvement of specific contact resistance of ohmic contacts. 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. 639-644). Trans Tech Publications, 778-780
Open this publication in new window or tab >>Applications of vapor-liquid-solid selective epitaxy of highly p-type doped 4H-SiC: PiN diodes with peripheral protection and improvement of specific contact resistance of ohmic contacts
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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. 639-644Conference paper, Published paper (Refereed)
Abstract [en]

This work deals with two applications of the Selective Epitaxial Growth of highly p-type doped buried 4H-SiC in Vapor-Liquid-Solid configuration (SEG-VLS). The first application is the improvement of the Specific Contact Resistance (SCR) of contacts made on such p-type material. As a result of the extremely high doping level, SCR values as low as 1.3x10-6 Ω.cm2 have been demonstrated. Additionally, the high Al concentration of the SEG-VLS 4H-SiC material induces a lowering of the Al acceptor ionization energy down to 40 meV. The second application is the fabrication of PiN diodes with SEG-VLS emitter and guard-rings peripheral protection. Influence of some process parameters and crystal orientation on the forward and reverse characteristics of the PiN diodes is discussed. © (2014) Trans Tech Publications, Switzerland.

Place, publisher, year, edition, pages
Trans Tech Publications, 2014
Series
Materials Science Forum, ISSN 0255-5476
Keywords
Ohmic contact; P-type 4H-SiC; PiN diode; Selective epitaxial growth; Vapor-liquid-solid
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-110537 (URN)10.4028/www.scientific.net/MSF.778-780.639 (DOI)000336634100151 ()2-s2.0-84896090012 (Scopus ID)9783038350101 (ISBN)
Conference
15th International Conference on Silicon Carbide and Related Materials, ICSCRM 2013
Available from: 2014-09-18 Created: 2014-09-12 Last updated: 2014-10-08
Chubarov, M., Pedersen, H., Högberg, H., Filippov, S., Engelbrecht, J. A., O'Connel, J. & Henry, A. (2014). Boron nitride: A new photonic material. Physica. B, Condensed matter, 439, 29-34
Open this publication in new window or tab >>Boron nitride: A new photonic material
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2014 (English)In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 439, p. 29-34Article in journal (Refereed) Published
Abstract [en]

Rhombohedral boron nitride (r-BN) layers were grown on sapphire substrate in a hot-wall chemical vapor deposition reactor. Characterization of these layers is reported in details. X-ray diffraction (XRD) is used as a routine characterization tool to investigate the crystalline quality of the films and the identification of the phases is revealed using detailed pole figure measurements. Transmission electron microscopy reveals stacking of more than 40 atomic layers. Results from Fourier Transform InfraRed (FTIR) spectroscopy measurements are compared with XRD data showing that FTIR is not phase sensitive when various phases of sp(2)-BN are investigated. XRD measurements show a significant improvement of the crystalline quality when adding silicon to the gas mixture during the growth; this is further confirmed by cathodoluminescence which shows a decrease of the defects related luminescence intensity.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Boron nitride; Epitaxy; XRD; TEM; FTIR; Cathodoluminescence
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105563 (URN)10.1016/j.physb.2013.10.068 (DOI)000331620700007 ()
Available from: 2014-03-31 Created: 2014-03-27 Last updated: 2017-12-05
Chubarov, M., Pedersen, H., Högberg, H., Czigany, Z. & Henry, A. (2014). Chemical vapour deposition of epitaxial rhombohedral BN thin films on SiC substrates. CrystEngComm, 16(24), 5430-5436
Open this publication in new window or tab >>Chemical vapour deposition of epitaxial rhombohedral BN thin films on SiC substrates
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2014 (English)In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, no 24, p. 5430-5436Article in journal (Refereed) Published
Abstract [en]

Epitaxial growth of rhombohedral boron nitride (r-BN) on different polytypes of silicon carbide (SiC) is demonstrated using thermally activated hot-wall chemical vapour deposition and triethyl boron and ammonia as precursors. With respect to the crystalline quality of the r-BN films, we investigate the influence of the deposition temperature, the precursor ratio (N/B) and the addition of a minute amount of silicon to the gas mixture. From X-ray diffraction and transmission electron microscopy, we find that the optimal growth temperature for epitaxial r-BN on the Si-face of the SiC substrates is 1500 degrees C at a N/B ratio of 642 and silicon needs to be present not only in the gas mixture during deposition but also on the substrate surface. Such conditions result in the growth of films with a c-axis identical to that of the bulk material and a thickness of 200 nm, which is promising for the development of BN films for electronic applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-108816 (URN)10.1039/c4ce00381k (DOI)000336839900032 ()
Available from: 2014-07-07 Created: 2014-07-06 Last updated: 2017-12-05
Li, X., Jacobson, H., Boulle, A., Chaussende, D. & Henry, A. (2014). Double-Position-Boundaries Free 3C-SiC Epitaxial Layers Grown on On-Axis 4H-SiC. ECS Journal of Solid State Science and Technology, 3(4), P75-P81
Open this publication in new window or tab >>Double-Position-Boundaries Free 3C-SiC Epitaxial Layers Grown on On-Axis 4H-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 4, p. P75-P81Article in journal (Refereed) Published
Abstract [en]

High quality double-position-boundaries free 3C-SiC epilayers have been successfully grown on on-axis (0001) 4H-SiC by chemical vapor deposition at optimized conditions as observed with optical microscopy and X-ray diffraction. The effect of the growth parameters, including temperature, C/Si ratio, ramp-up condition, Si/H-2 ratio, N-2 addition and pressure, on the quality of the grown layers is investigated. Different techniques, including microscopic and spectroscopic techniques, are used to characterize the epilayers. High resolution X-ray diffraction shows 2 theta-omega curve with full width at half maximum of only 16 arcsec for the (111) reflection detected from a 35 mu m thick 3C-SiC layer, showing the good structural quality of the layer. Reciprocal space maps confirm the absence of double-position-boundaries in a large depth of the layers. Low temperature photoluminescence measurement shows clear near-bandgap emission with sharp and single peaks, which further verifies the high quality of the epilayers.

Place, publisher, year, edition, pages
Electrochemical Society, 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-106298 (URN)10.1149/2.012404jss (DOI)000333570300008 ()
Available from: 2014-05-06 Created: 2014-05-05 Last updated: 2017-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5768-0244

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