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Critical issues for homoepitaxial GaN growth by molecular beam epitaxy on hydride vapor-phase epitaxy-grown GaN substrates

TitleCritical issues for homoepitaxial GaN growth by molecular beam epitaxy on hydride vapor-phase epitaxy-grown GaN substrates
Publication TypeJournal Article
Year of Publication2016
AuthorsStorm, DF, Hardy, MT, Katzer, DS, Nepal, N, Downey, BP, Meyer, DJ, McConkie, TO, Zhou, L, Smith, DJ
JournalJournal of Crystal Growth
Volume456
Pagination121-132
Date Published12
Type of ArticleArticle
ISBN Number0022-0248
Accession NumberWOS:000389590400020
Keywordsalgan/gan, ammonothermal gan, bulk, Crystallography, dislocation-density, gallium nitride, heterostructures, high-temperature limitations, ingan laser-diodes, interfaces, light-emitting-diodes, Line Defects, Materials Science, Molecular beam epitaxy, nitrides, physics, Substrates, surface polarity, thermal-stability, void-assisted separation
Abstract

While the heteroepitaxial growth of gallium nitride-based materials and devices on substrates such as SiC, sapphire, and Si has been well-documented, the lack of a cost-effective source of bulk GaN crystals has hindered similar progress on homoepitaxy. Nevertheless, freestanding GaN wafers are becoming more widely available, and there is great interest in growing GaN films and devices on bulk GaN substrates, in order to take advantage of the greatly reduced density of threading dislocations, particularly for vertical devices. However, homoepitaxial GaN growth is far from a trivial task due to the reactivity and different chemical sensitivities of N-polar (000 (1) under bar) and Ga-polar (0001) GaN surfaces, which can affect the microstructure and concentrations of impurities in homoepitaxial GaN layers. In order to achieve high quality, high purity homoepitaxial GaN, it is necessary to investigate the effect of the ex situ wet chemical clean, the use of in situ cleaning procedures, the sensitivity of the GaN surface to thermal decomposition, and the effect of growth temperature. We review the current understanding of these issues with a focus on homoepitaxial growth of GaN by molecular beam epitaxy (MBE) on c-plane surfaces of freestanding GaN substrates grown by hydride vapor phase epitaxy (HVPE), as HVPE-grown substrates are most widely available. We demonstrate methods for obtaining homoepitaxial GaN layers by plasma-assisted MBE in which no additional threading dislocations are generated from the regrowth interface and impurity concentrations are greatly reduced. Published by Elsevier B.V.

DOI10.1016/j.jcrysgro.2016.08.047
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Short TitleJ. Cryst. Growth
Alternate JournalJ. Cryst. Growth