Formation of InAs islands on InP (001) by droplet hetero-epitaxy

We have successfully obtained InAs islands on InP (001) by a novel droplet hetero-epitaxy using low-pressure organometallic vapor phase epitaxy (LP-OMVPE). The island growth sequence was initiated by trimethylindium (TMIn) supply in H, atmosphere which was intended to form In droplets and followed by tertiarybutylarsine (TBAs) supply after the TMIn supply was stopped at a growth temperature. By this process, large islands of which height was above 100 nm with clear facets were observed under atomic force microscope (AFM). Using a modified sequence in which the TMIn supply was stopped and the substrate temperature was lowered before the TBAs supply, the appearance of the islands was drastically changed. In the specimen prepared by this sequence at the same substrate temperature, small islands of about 10 nm in height were observed together with the large islands. In order to form smaller islands and to suppress formation of the large islands, the substrate temperature dependence of the islands from 530 to 610°C were investigated. The smallest islands with the height of 5 nm were obtained at the substrate temperature of 565°C.