氢化物气相外延生长GaN膜性质研究

摘要

利用氢化物气相外延技术在c 面蓝宝石上生长得到纤锌矿结构 GaN 膜.采用高分辨 X 射线衍射、拉曼光谱和光致发光谱对GaN 外延膜进行了结构表征和光学性质研究,重点探讨了光致发光谱的温度变化特性.样品(002)面和(102)面摇摆曲线半高宽分别为322和375 arcsec,表明生长的 GaN 膜具有较好的晶体质量.高分辨 X射线衍射、拉曼光谱和光致发光谱测试表明,外延膜中存在0．26 GPa 的面内压应力.变温光致发光谱研究发现 GaN 外延膜中 A 自由激子发射峰和施主束缚激子发射峰随温度变化服从能带收缩理论.但由于 A 自由激子单声子伴峰可能是一种与自由激子动能变化相关的自由激子-声子相互作用的复合机制,导致其峰位呈现先蓝移后红移变化,以及其积分强度出现先增加后降低的现象.%The high crystal quality GaN film has been successfully grown by hydride vapor phase epitaxy (HVPE)and the properties of GaN epilayers have been investigated by high-resolution X-ray diffraction (HRXRD),Raman and photoluminescence (PL)measurements.The temperature dependence of photolumines-cence has been studied particularly.X-ray rocking curves (XRC)showed that the full widths at half maximum (FWHM)of (002 )and (102 )were 322 and 375 arcsec,respectively.Temperature-dependent PL spectra showed that the neutral donor bound excitons (D0 X)emission and free A-excitons recombination peaks reflected the shrinkage of the band gap,but the peak energy and the integrated intensity of 1-longitudinal optical (LO) phonon replica of the free A-excitons exhibited non-monotonic variations with increasing temperature,which might be related to the exciton-polariton dispersion effects of the free excitons caused by gain extra kinetic ener-gy with increasing temperature.HRXRD measurements,Raman and PL spectra all revealed that biaxial in-plane compressive strain (about 0.26 GPa)existed in the GaN layer and the results deduced from the three methods were in good agreement.