In this work, a method to acquire freestanding GaN by using low temperature (LT)-GaN layer was put forward. To obtain porous structure and increase the crystallinity, LT-GaN layers were annealed at high temperature. The morphology of LT-GaN layers with different thickness and annealing temperature before and after annealing was analyzed. Comparison of GaN films using different LT-GaN layers was made to acquire optimal LT-GaN process. According to HRXRD and Raman results, GaN grown on 800 nm LT-GaN layer which was annealed at 1090 °C has good crystal quality and small stress. The GaN film was successfully separated from the substrate after cooling down. The self-separation mechanism of this method was discussed. Cross-sectional EBSD mapping measurements were carried out to investigate the effect of LT-buffer layer on improvement of crystal quality and stress relief. The optical property of the obtained freestanding GaN film was also determined by PL measurement.

在这项工作中，提出了一种通过使用低温（LT）-GaN层获得自立式GaN的方法。为了获得多孔结构并增加结晶度，将LT-GaN层在高温下退火。分析了退火前后不同厚度和退火温度的LT-GaN层的形貌。对使用不同LT-GaN层的GaN膜进行比较，以获得最佳的LT-GaN工艺。根据HRXRD和Raman结果，在1090°C退火的800 nm LT-GaN层上生长的GaN具有良好的晶体质量和较小的应力。冷却后，成功将GaN膜与衬底分离。讨论了该方法的自分离机理。进行了EBSD横截面图测量，以研究LT缓冲层对改善晶体质量和缓解应力的影响。还通过PL测量来确定所获得的独立式GaN膜的光学性质。