用光荧光谱和原子力显微镜测试技术系统研究了在2 nm In0.2Ga0.8As和x ML GaAs的复合应力缓冲层上生长的InAs/GaAs自组织量子点的发光特性和表面形貌.采用In0.2Ga0.8As与薄层GaAs复合的应力缓冲层,由于减少了晶格失配度致使量子点密度从约1.7×109 cm-2显著增加到约3.8×109cm-2.同时,复合层也有利于提高量子点中In的组份,使量子点的高宽比增加,促进量子点发光峰红移.对于x=10 ML的样品室温下基态发光峰达到1350 nm.

Optical properties and surface structures of InAs/GaAs selfassembled quantum dots(QDs) grown on 2 nm In_(0.2)Ga_(0.8)As and x ML GaAs combined strain-buffer layer were investigated systematically by photoluminescence(PL) and atomic force microscopy(AFM).The QD density increased from ~1.7×10~9 cm~(-2) to ~3.8×10~9 cm~(-2) due to the decreasing of the lattice mismatch.The combined layer was of benefit to increasing In incorporated into dots and the average height-to-width ratios,which resulted in the red-shift of the emission peaks.For the sample of x= 10 ML,the ground state transition is shifted to 1350 nm at room temperature.