Optimization of low temperature GaN buffer layers for halide vapor phase epitaxy growth of bulk GaN

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• 作者：Carl Hemmingsson ; ^{cah@ifm.liu.se} ; Galia Pozina
• 关键词：A1. Crystal morphology ; A1. Interfaces ; A1. Roughening ; A2. Growth from vapor ; A3. Hydride vapor phase epitaxy ; B1. Nitrides
• 刊名：Journal of Crystal Growth
• 出版年：2013
• 出版时间：1 March, 2013
• 年：2013
• 卷：366
• 期：Complete
• 页码：61-66
• 全文大小：1347 K

文摘

We have studied growth and self-separation of bulk GaN on c-oriented Al₂O₃ using low temperature (LT) GaN buffer layers. By studying the X-ray diffraction (XRD) signature for the asymmetric and symmetric reflections versus the LT-GaN thickness and V/III precursor ratio, we observe that the peak width of the reflections is minimized using a LT buffer thickness of ¡«100-300 nm. It was observed that the V/III precursor ratio has a strong influence on the morphology. In order to obtain a smooth morphology, the V/III precursor ratio has to be more than 17 during the growth of the buffer layer. By using an optimized LT buffer layer for growth of a 20 ¦Ìm thick GaN layer, we obtain a XRD peak with a full width at half maximum of ¡«400 and ¡«250 arcs for (002) and (105) reflection planes, respectively, and with a dark pit density of ¡«2.2¡Á10⁸ cm^?2. For layers thicker than 1 mm, the GaN was spontaneously separated and by utilizing this process, thick free freestanding 2¡å GaN substrates were manufactured.