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MOCVD生长的GaN和GaN:Mg薄膜的拉曼散射
引用本文:王瑞敏,陈光德,LIN J Y,JIANG H X.MOCVD生长的GaN和GaN:Mg薄膜的拉曼散射[J].发光学报,2005,26(2):229-232.
作者姓名:王瑞敏  陈光德  LIN J Y  JIANG H X
作者单位:1. 西安交通大学 理学院,陕西 西安 710049
2. Department of Physics,Kansas State University,Manhattan,Kansas 66506,USA
摘    要:通过显微拉曼散射对用金属有机化学气相沉积(MOCVD)法在Al2O3衬底上生长的六方相CaN和掺Mg的P型GaN薄膜进行了研究。在两个样品的拉曼散射谱中同时观察到位于640,660cm^-1附近的两个峰。640cm^-1的峰归因于布里渊区边界(L点)最高声学声子的二倍频,而660cm^-1的峰为布里渊区边界的光学声子支或缺陷诱导的局域振动模。掺Mg的GaN在该处的峰型变宽是Mg诱导的缺陷引起的加宽或Mg的局域模与上述两峰叠加的结果。在掺Mg的样品中还观察到276,376cm^-1几个局域模并给予了解释。同时掺Mg的GaN中出现了应力弛豫的现象,掺Mg引起的失配位错和电子-声子相互作用都有可能对E2模的频率产生影响。

关 键 词:氮化镓  拉曼散射  应力松弛
文章编号:1000-7032(2005)02-0229-04
修稿时间:2004年5月8日

Raman Scattering of GaN and Mg-doped GaN Films Grown by MOCVD
WANG Rui-min,CHEN Guang-de,LIN J Y,JIANG H X.Raman Scattering of GaN and Mg-doped GaN Films Grown by MOCVD[J].Chinese Journal of Luminescence,2005,26(2):229-232.
Authors:WANG Rui-min  CHEN Guang-de  LIN J Y  JIANG H X
Abstract:Raman scattering spectra of GaN and Mg-doped GaN films grown by metal-organic chemical-vapor deposition (MOCVD) on sapphire substrate are investigated. Some weak peaks are also observed in two spectra besides the allowed E 2 and A 1(LO) phonon modes in Z(X-)Z backscattering geometry. The origins of these peaks are discussed and the differences between two spectra are compared. Two peaks at 640 and 660 cm -1 are observed both in the spectra of GaN and Mg-doped GaN samples. The 640 cm -1 peak is attributed to an overtone process of the highest acoustic-phonon branch at the zone boundary (L point). The peak at 660 cm -1 is attributed to the optical-phonon branch at the zone boundary or the local vibrational mode induced by defect. In the spectrum of Mg-doped GaN sample there is a broad feature near the two peaks. It is suggested that the broad feature arises from the local vibrational mode of Mg-N bond which superposed on the two peaks mentioned above or arises from defect-induced broaden. Two additional peaks at 276 cm -1 and 376 cm -1 are also observed in the spectrum of Mg-doped GaN sample. The peak at 276 cm -1 is the local vibrational mode of Mg-N bond and the peak at 376 cm -1 is the local vibrational mode of impurity- defect complex. The frequency of E 2 mode in Mg-doped GaN shifted to low energy side compared with GaN sample, and located at 568 cm -1 at room temperature. This indicated that the relaxation of residual stress existed in Mg-doped sample. The stress relaxation is contributed to Mg-induced generation of dislocation. Furthermore, electron-phonon interaction also can induce frequency shift of E 2 mode.
Keywords:GaN  Raman scattering  stress relaxation
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