生长在尖晶石衬底上的GaN外延层的喇曼散射研究

Raman Scattering of GaN Epilayer Grown on MgAl 2O 4 Substrate

在室温下测量了用ＭＯＶＰＥ方法生长在尖晶石（ＭｇＡｌ２Ｏ４）衬底上的ＧａＮ外延层的一阶喇曼光谱．应用各种背散射和９０°散射配置，测得了除低频Ｅ２模外所有ＧａＮ的喇曼活性光学声子模．并且在Ｘ（Ｚ，Ｘ）Ｚ和Ｘ（Ｙ，Ｙ）Ｚ配置下观测到了由Ａ１和Ｅ２模混合形成的准ＴＯ和准ＬＯ模．

Abstract First order Raman spectra of GaN epilayer grown by MOVPE on MgAl 2O 4 substrate were measured at room temperature. By using various back and rightangle scattering geometry, all symmetry allowed optical phonons were observed, except the low frequancy E 2 mode. The quasitransverse Q (TO) and quasilongitudinal Q (LO) modes were also observed in the X(Z,X)Z and X(Y,Y)Z configurations, which have the mixed A 1 and E 1 symmetry character. All the results are in good agreement with the group theoretical selection rules.