GaAs/InGaAs应变异质结构临界厚度的Raman散射和PL谱分析

采用室温Raman散射和低温光致发光(PL)谱,对以TMG,固体As和固体In作为分子束源的MOMBE法生长的GaAs/In_xGa_(1-x)As(x=0.3)单层异质结构和多量子阱结构中InGaAs应变层的临界厚度进行了实验研究。由应变引起的Raman散射峰位移,以及PL谱峰位置与应变和无应变状态下一维有限深势阱跃迁能量计算结果的比较可见,在In组分含量x=0.3的情况下,临界厚度H_c≤5nm,小于能量平衡理论的结果,而与力学平衡模型的理论值相近。

Analysis of Critical Layer Thickness in GaAs/InGaAs Strained Heterostructures by Raman Scattering and Photoluminescence

The critical layer thickness for InGaAs layers in GaAs/ InxGa1-xAs (x=0.3) single strained heterostructures and multiple strained quantum wells grown by metalorganic molecular beam epitaxy (MOMBE)using trimethylgallium (TMG) , solid arsenic and solid indium as source materials has been investigated ex-perimentally by Raman scattering and photoluminescence (PL). By analysing the Raman scattering peak shifts induced by strain and (IC-lH)transition energies ob-tained from PL measurement and theoretical calculation,the critical layer thickness determined for In0.3Ga0.7As layers grown on GaAs substrates is about 5 nm,which is near the theoretical prediction of the mechanical equilibrium model and is much lower than the result obtained by the energy balance model.