Temperature dependence of biaxial strain and its influence on phonon and band gap of GaN thin film

作     者：徐宏妍 菅傲群 薛晨阳 陈阳 张斌珍 张文栋 张志国 冯震 

作者机构：Key Laboratory of Instrumentation Science & Dynamic Measurement (North University of China) Ministry of Education National Key Laboratory for Electronic Measurement Technology North University of China The 13th research institute of CETC 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2008年第17卷第6期

页      面：2245-2250页

核心收录：

学科分类：08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0704[理学-天文学] 

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos 50405025 and 50535030) Program for New Century Excellent Talents in University, China 

主　　题：biaxial strain phonon band gap GaN 

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 100K 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 E2^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 exeiton 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-inereasing shift of the energy in a temperature range from 100 K to 823 K.