On the nucleation, coalescence, and overgrowth of HVPE GaN on misoriented sapphire substrates and the origin of pinholes

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• 作者：Tim Bohnen ; Aryan E.F. de Jong ; Willem J.P. van Enckevort ; Jan L. Weyher ; Gerbe W.G. van Dreumel ; Hina Ashraf ; Paul R. Hageman ; Elias Vlieg
• 关键词：A1. Nucleation ; A1. Defects ; A3. Hydride vapor phase epitaxy ; B1. Nitrides ; B2. Semiconducting gallium compounds
• 刊名：Journal of Crystal Growth
• 出版年：2009
• 出版时间：1 December 2009
• 年：2009
• 卷：311
• 期：23-24
• 页码：4685-4691
• 全文大小：654 K

文摘

The nucleation of HVPE GaN on misoriented sapphire substrates and the transition from the nucleation layer to an epitaxial film were investigated. After a KOH/NaOH eutectic etch of the approximately thick GaN layer, grown on sapphire using a low temperature nucleation, high temperature epitaxy process, the cross-sections revealed columnar structures, up to roughly above the sapphire substrate. Photoetching of the thick GaN layers revealed inhomogeneous defect distributions along the cross-sections, which appeared to be related to the numerous pinholes originating at the GaN/sapphire interface. We present a model explaining the formation of pinholes by the coalescence of the GaN nuclei during the epitaxial overgrowth.