A study into the impact of sapphire substrate orientation on the properties of nominally-undoped β-Ga<inf>2</inf>O<inf>3</inf> thin films grown by pulsed laser deposition

Teherani, FH; Rogers, DJ; Sandana, VE; Bove, P; Ton-That, C; Lem, LLC; Chikoidze, E; Neumann-Spallart, M; Dumont, Y; Huynh, T; Phillips, MR; Chapon, P; McClintock, R; Razeghi, M

A study into the impact of sapphire substrate orientation on the properties of nominally-undoped β-Ga<inf>2</inf>O<inf>3</inf> thin films grown by pulsed laser deposition

Teherani, FH Rogers, DJ Sandana, VE Bove, P Ton-That, C

Lem, LLC Chikoidze, E Neumann-Spallart, M Dumont, Y Huynh, T Phillips, MR

Chapon, P McClintock, R Razeghi, M

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Publication Type:: Conference Proceeding
Citation:: Proceedings of SPIE - The International Society for Optical Engineering, 2017, 10105
Issue Date:: 2017-01-01

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Field	Value	Language
dc.contributor.author	Teherani, FH	en_US
dc.contributor.author	Rogers, DJ	en_US
dc.contributor.author	Sandana, VE	en_US
dc.contributor.author	Bove, P	en_US
dc.contributor.author	Ton-That, C https://orcid.org/0000-0003-3276-1739	en_US
dc.contributor.author	Lem, LLC	en_US
dc.contributor.author	Chikoidze, E	en_US
dc.contributor.author	Neumann-Spallart, M	en_US
dc.contributor.author	Dumont, Y	en_US
dc.contributor.author	Huynh, T	en_US
dc.contributor.author	Phillips, MR https://orcid.org/0000-0003-1522-9281	en_US
dc.contributor.author	Chapon, P	en_US
dc.contributor.author	McClintock, R	en_US
dc.contributor.author	Razeghi, M	en_US
dc.date.available	2017-03-23	en_US
dc.date.issued	2017-01-01	en_US
dc.identifier.citation	Proceedings of SPIE - The International Society for Optical Engineering, 2017, 10105	en_US
dc.identifier.isbn	9781510606517	en_US
dc.identifier.issn	0277-786X	en_US
dc.identifier.uri	http://hdl.handle.net/10453/88426
dc.description.abstract	© 2017 SPIE. Nominally-undoped Ga2O3 layers were deposited on a-, c- and r-plane sapphire substrates using pulsed laser deposition. Conventional x-ray diffraction analysis for films grown on a- and c-plane sapphire showed the layers to be in the β-Ga2O3 phase with preferential orientation of the (-201) axis along the growth direction. Pole figures revealed the film grown on r-plane sapphire to also be in the β-Ga2O3 phase but with epitaxial offsets of 29.5°, 38.5° and 64° from the growth direction for the (-201) axis. Optical transmission spectroscopy indicated that the bandgap was ∼5.2eV, for all the layers and that the transparency was > 80% in the visible wavelength range. Four point collinear resistivity and Van der Pauw based Hall measurements revealed the β-Ga2O3 layer on r-plane sapphire to be 4 orders of magnitude more conducting than layers grown on a- and c-plane sapphire under similar conditions. The absolute values of conductivity, carrier mobility and carrier concentration for the β-Ga2O3 layer on r-sapphire (at 20Ω-1.cm-1, 6 cm2/Vs and 1.7 x 1019 cm-3, respectively) all exceeded values found in the literature for nominally-undoped β-Ga2O3 thin films by at least an order of magnitude. Gas discharge optical emission spectroscopy compositional depth profiling for common shallow donor impurities (Cl, F, Si and Sn) did not indicate any discernable increase in their concentrations compared to background levels in the sapphire substrate. It is proposed that the fundamentally anisotropic conductivity in β-Ga2O3 combined with the epitaxial offset of the (-201) axis observed for the layer grown on r-plane sapphire may explain the much larger carrier concentration, electrical conductivity and mobility compared with layers having the (-201) axis aligned along the growth direction.	en_US
dc.relation.ispartof	Proceedings of SPIE - The International Society for Optical Engineering	en_US
dc.relation.isbasedon	10.1117/12.2262757	en_US
dc.title	A study into the impact of sapphire substrate orientation on the properties of nominally-undoped β-Ga<inf>2</inf>O<inf>3</inf> thin films grown by pulsed laser deposition	en_US
dc.type	Conference Proceeding
utslib.citation.volume	10105	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CCET - Centre for Clean Energy Technology
utslib.copyright.status	open_access
pubs.publication-status	Published	en_US
pubs.volume	10105	en_US

Abstract:

© 2017 SPIE. Nominally-undoped Ga2O3 layers were deposited on a-, c- and r-plane sapphire substrates using pulsed laser deposition. Conventional x-ray diffraction analysis for films grown on a- and c-plane sapphire showed the layers to be in the β-Ga2O3 phase with preferential orientation of the (-201) axis along the growth direction. Pole figures revealed the film grown on r-plane sapphire to also be in the β-Ga2O3 phase but with epitaxial offsets of 29.5°, 38.5° and 64° from the growth direction for the (-201) axis. Optical transmission spectroscopy indicated that the bandgap was ∼5.2eV, for all the layers and that the transparency was > 80% in the visible wavelength range. Four point collinear resistivity and Van der Pauw based Hall measurements revealed the β-Ga2O3 layer on r-plane sapphire to be 4 orders of magnitude more conducting than layers grown on a- and c-plane sapphire under similar conditions. The absolute values of conductivity, carrier mobility and carrier concentration for the β-Ga2O3 layer on r-sapphire (at 20Ω-1.cm-1, 6 cm2/Vs and 1.7 x 1019 cm-3, respectively) all exceeded values found in the literature for nominally-undoped β-Ga2O3 thin films by at least an order of magnitude. Gas discharge optical emission spectroscopy compositional depth profiling for common shallow donor impurities (Cl, F, Si and Sn) did not indicate any discernable increase in their concentrations compared to background levels in the sapphire substrate. It is proposed that the fundamentally anisotropic conductivity in β-Ga2O3 combined with the epitaxial offset of the (-201) axis observed for the layer grown on r-plane sapphire may explain the much larger carrier concentration, electrical conductivity and mobility compared with layers having the (-201) axis aligned along the growth direction.

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http://hdl.handle.net/10453/88426