利用液滴狀磊晶成長方式在矽(111)基板上成長氮化鎵量子點

Abstract

GaN nanodots（NDs）were fabricated on Si（111）substrates by droplet epitaxy using Plasma-Assisted Molecular Beam Epitaxy (PA-MBE) system. In ultra-high vacuum condition, Ga metallic droplets formed, and then became GaN NDs by nitridation process. The density of GaN NDs can be controlled by the growth temperatures between 475 and 550°C, the nitridation time within the range 5-10 minutes, and the Si（111）substrates with and without pre-nitridation 60 minutes. Field emission scanning electron microscopy（FESEM）was used for the investigation of density and surface morphology of GaN NDs on Si （111）. We can find the density of GaN NDs increases as the growth temperature decreases. By increasing the nitridation time, we observed GaN NDs density increase. The pre-nitridation treatment for 60 minutes of Si（111）substrates can also increase GaN NDs density. The results of X-ray photoelectron spectroscopy（XPS）confirm that Ga droplets that transformed into GaN NDs and self-assembled over the sample surface during nitridation. Transmission Electron Microscopy（TEM）was used for the investigation of surface distribution, crystalline quality and shape of GaN NDs. From the results of experiments, we demonstrated that density of GaN NDs grown by droplet epitaxy strongly affected by growth temperature, nitridation time and pre-nitridation treatment of the Si（111）substrates. Meanwhile, the growth mechanism of GaN NDs was proposed in this study.