%0 Journal Article
%T Temperature dependence of biaxial strain and its influence on phonon and band gap of GaN thin film<br>
%A Xu Hong-Yan
%A Jian Ao-Qun
%A Xue Chen-Yang
%A Chen Yang
%A Zhang Bin-Zhen
%A Zhang Wen-Dong
%A Zhang Zhi-Guo
%A Feng Zhen
%A <br>
%J 中国物理 B
%D 2008
%I 
%X 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.
%K biaxial strain
%K phonon
%K band gap
%K GaN<br>
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=6E709DC38FA1D09A4B578DD0906875B5B44D4D294832BB8E&cid=47EA7CFDDEBB28E0&jid=CD8D6A6897B9334F09D8D1648C376FB4&aid=EA897E4140306B239E534D25CB05139B&yid=67289AFF6305E306&vid=BCA2697F357F2001&iid=B31275AF3241DB2D&sid=3BC12457BF33B266&eid=28C569C68A441089&journal_id=1009-1963&journal_name=中国物理&referenced_num=0&reference_num=0