CONTROL OF THE ARRANGEMENT OF THE NATIVE GALLIUM VACANCIES IN GA2SE3 ON (100)GAAS BY MOLECULAR-BEAM EPITAXY

We attempted to control the arrangement of the native Ga vacancies in Ga2Se3 films on (100)GaAs substrates by molecular beam epitaxy. When t he GaAs substrates were heat-treated at 550 degrees C before growth, t he vacancy-ordered superstructure was formed in the [01 (1) over bar] direction, which is different from the ordering direction in Ga2Se3 on (100)GaP. On the other hand, when the heat treatment was not carried out, the ordering direction was [011] at growth temperatures below 500 degrees C. These results indicate that the initial stage of the growt h affects the ordering direction in Ga2Se3 on (100)GaAs. We have succe ssfully controlled the ordering direction by introducing a Ga2Se3 buff er layer grown at low temperature. Furthermore, we investigated the ef fects of the growth conditions on the ordering of the Ga vacancies in Ga2Se3 films on (100)GaAs, and it was found that the vacancy ordering was highly developed at high VI/III ratio and low growth temperature.