Heteroepitaxial Mechanism of Ouantum-Effect Semiconductors

利用原子力显微镜（AFM）、高分辨率透射电镜（hrtem）和光致发光技术研究了GaAs/InAs/GaAs自组装量子结构的异向机制。对于多层GaAs/InAs/GaAs结构，1)需要100a厚的GaAs层来嵌入InAs点，2)在GaAs势垒层下存在的InAs点上形成InAs量子点，3)在高激发条件下可以观察到InAs量子点中较高的量子能级而发光。研究了氮化镓/氮化镓异质外延的初始阶段，以实现氮化镓基量子点。从理论角度出发，利用价力场模型对自组装量子点二维到三维过渡的应变分布和过渡厚度进行了数值计算。我们成功地用解析法得到了跃迁厚度的一般规律。

We have investigated the heteropitaxial mechanism of GaAs/InAs/GaAs self-assembled quantum structure by using atomic force microscopy (AFM), high resolution transmission electron microscopy (HR-TEM), and photoluminescence measurement. For multi-stacked GaAs/InAs/GaAs structure, 1) 100A-thick GaAs layr is required to embed the InAs dots, 2) InAs quantum dots are formed on the InAs dots exist under the GaAs barrier layrs, 3) luminescence due to higher quantum-level in the InAs quantum dots can be observed under the high excitation condition. Initial stage of GaInN/GaN heteroepitaxy also investigated to achieve an nitride based quantum-dots. From the theoretical approach, strain distribution and transition thickness of 2D to 3D transition for self-assembled quantum dots are carried out by using numerical calculation based on the valence-force-field model. We have successfully obtained a general law of transition thickness by analytical approach.