MOCVD生长Si衬底上HT-AlN缓冲层低生长压力对GaN薄膜的影响

采用金属有机化学气相沉积（MOCVD）技术在Si（111）衬底上外延GaN薄膜，对高温AlN（HT-AlN）缓冲层在小范围内低生长压力（6.7~16.6 kPa）条件下对GaN薄膜特性的影响进行了研究。研究结果表明GaN外延层的表面形貌、结构和光学性质对HT-AlN缓冲层的生长压力有很强的的依赖关系。增加HT-AlN缓冲层的生长压力，GaN薄膜的光学和形貌特性均有明显改善，当HT-AlN缓冲层的生长压力为13.3 kPa时，得到无裂纹的GaN薄膜，其（002）和（102）面的X射线衍射峰值半高宽分别为735 arcsec和778 arcsec，由拉曼光谱计算得到的张应力为0.437 GPa，原子力显微镜（AFM）观测到表面粗糙度为1.57 nm。

Effect of Low Growth Pressure of HT-AlN Buffer on GaN Epilayer Grown on Si(111)

GaN films were grown on Si (111) substrates by metal-organic chemical vapor deposition (MOCVD). The influence of high temperature AlN(HT-AlN) buffer low various growth pressure (6.7-16.6 kPa) on GaN films was studied. It is found that, the surface morphology and structural and optical properties of the GaN epilayer strongly depend on HT-AlN buffer growth pressure. Increase the growth pressure of HT-AlN buffer, the optical and morphology properties of GaN film are both significantly improved, when the growth pressure of HT-AlN buffer layer was at 13.3 kPa, we obtained a crack-free GaN film, the XRD FWHM of (002) and (102) plane of GaN film are 735 and 778 arcsec, respectively. The tensile stress calculated from Raman spectra is 0.437 GPa, and RMS roughness of AFM 5 μm×5 μm scan is 1.57 nm.