High-quality GaAs quantum dots grown using a modified droplet epitaxy technique

We proposed a new modified droplet epitaxy method using a sulfur-termination (S-termination) process and demonstrated the fabrication of high-quality GaAs/AlGaAs quantum dot (QD) structures. Three-dimensional GaAs microcrystals with almost the same base sizes as Ga droplets were successfully grown at room temperature by As4 flux irradiation to the droplets deposited on the substrate. By subsequent S-termination, the shapes of the GaAs microcrystals were preserved up to about 535 .deg. C, resulting in both improvement of QDs crystallinity and a growth of a high-quality overlayer. Quantum-size effects were distinctly observed by using photoluminescence measurements. This modified droplet epitaxy method was confirmed to be useful for self-assembled formation of GaAs QDs