Patterned GeSn Strip Growth on Si By Sn Self-Catalyzed Method

Abstract

GeSn has been attracted much attention in recent years due to its direct band characteristic. However, due to the large lattice mismatch and the low solid solubility of Sn in Ge, the growth of GeSn on Si is still a challenge. Thick-layer GeSn alloy have been grown by molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) by applying the low-temperature-grown Ge buffer layer, but there is still high the dislocation density(more than 107cm-2) and it limits its application in optoelectronics. We have reported a simple way to grow the defect-free GeSn alloy strips on Si substrates with the assistance of Sn metal. It can be lateral grown on Si(111) by Sn self-catalyzed method. The GeSn materials are grown in a MBE system with a base pressure of 5 × 10−8 Pa. Here we will report our recent progress of the growth of GeSn wires and GeSn pattern on pattered substrate. It is found that GeSn materials can be selected grown in the patterned window. The size of wires can be down to 100 nm. We can grow 10x10 GeSn pattern with size of 2um x 2 um and 5 um x 5um. Here we will also discuss the growth mechanism and the impact factors on the growth of GeSn materials. It is found that Sn has an important impact on morphology of the GeSn wires and different depositions and annealing times of Sn will impact their morphology. GeSn alloy strips show a good quality by the TEM micrographs and the SAED patterns. It has an important application in Si based laser and photodetectors.