中国物理B ›› 2008, Vol. 17 ›› Issue (6): 2245-2250.doi: 10.1088/1674-1056/17/6/051
徐宏妍1, 菅傲群1, 薛晨阳1, 陈阳1, 张斌珍1, 张文栋1, 张志国2, 冯震2
Xu Hong-Yan(徐宏妍)a)b), Jian Ao-Qun(菅傲群)a)b)†, Xue Chen-Yang(薛晨阳)a)b),Chen Yang(陈阳)a)b), Zhang Bin-Zhen(张斌珍)a)b), Zhang Wen-Dong(张文栋)a)b), Zhang Zhi-Guo(张志国)c), and Feng Zhen(冯震)c)
摘要: Hexagonal GaN epilayer grown on sapphire substrate by metal organic chemical vapour deposition (MOCVD) is studied using Raman scattering and photoluminescence in a temperature range from 100\,K to 873\,K. The model of strain (stress) induced by the different lattice parameters and thermal coefficients of epilayer and substrate as a function of temperature is set up. The frequency and the linewidth of $E_2^{\rm high}$ mode in a GaN layer are modelled by a theory with considering the thermal expansion of the lattice, a symmetric decay of the optical phonons, and the strain (stress) in the layer. The temperature-dependent energy shift of free exciton A is determined by using Varshni empirical relation, and the effect of strain (stress) is also investigated. We find that the strain in the film leads to a decreasing shift of the phonon frequency and an about 10meV-increasing shift of the energy in a temperature range from 100\,K to 823\,K.
中图分类号: (Thin film structure and morphology)