利用高分辨X射线衍射(HRXRD)与拉曼散射光谱(Raman scattering spectra)研究了氮化处理与低温AlN缓冲层对低压金属有机化学气相沉积(LP-MOCVD)在r面蓝宝石衬底上外延的a面GaN薄膜中的残余应变的影响。实验结果表明: 与氮化处理后生长的a-GaN相比，使用低温AlN缓冲层后生长的a-GaN具有较小的摇摆曲线的半高宽和较低的残余应变，而且其结构各向异性和残余应变各向异性也均有一定程度的降低。因此，与氮化处理相比，低温AlN缓冲层更有利于a-GaN的生长。

The effect of nitridation treatment and the low temperature (LT) AlN buffer on structure and strain of a-plane GaN epilayers grown on r-plane sapphire by low pressure metalorganic chemical vapor deposition (LP-MOCVD) has been investigated by high resolution X-ray diffraction (HRXRD) and polarized Raman scattering spectra in backscattering configurations. For the sample using the LT-AlN buffer, the full widths at half maximum (FWHM) of X-ray rocking curves (XRC) and the strain of a-plane GaN are lower comparing with that of the sample with nitridation, which is consistent with the smaller in-plane stress anisotropic distribution in a-plane GaN epilayers with LT-AlN buffer.