低温GaAs外延层上生长InAs量子点的研究

STUDY OF SELF-ASSEMBLED InAs QUANTUM DOTS GROWN ON LOW TEMPERATURE GaAs EPI-LAYER

利用退火技术 ,实现了在低温 Ga As外延层上 In As量子点的生长 .透射电镜 (TEM)研究表明 ,低温 Ga As外延层上生长的 In As量子点比通常生长的 In As量子点明显变小 ,且密度变大 ,认为是由于低温 Ga As中的点缺陷以及 As沉淀引起的 :点缺陷释放了部分弹性能 ,使得量子点变小 ,而 As沉淀可能是量子点密度变大的原因 .在光致发光谱 (PL )上 ,退火低温外延层上生长的量子点的发光峰能量较高 。

InAs self organized quantum dots(QDs) grown on annealed low temperature GaAs (LT GaAs) epi layer were investigated by transmission electron microscopy (TEM) and photoluminescence (PL) measurement. TEM showed that QDs formed on annealed LT GaAs epi layer have a smaller size and a higher density than QDs formed on normal GaAs buffer layer. In addition, the PL spectra analysis showed that the LT GaAs epi layer resulted in a blue shift in peak energy, and a narrower linewidth in the PL peak. The differences were attributed to the point defects and As precipitates in annealed LT GaAs epi layer for the point defects and As precipitates change the strain field of the surface. The results provide a method to improve the uniformity and change the energy band structure of the QDs by controlling the defects in the LT GaAs epi layer.