Crystal structure of low-temperature-grown In0.45Ga0.55As on an InP substrate

Abstract

We grew low-temperature-grown (LTG) In0.45Ga0.55As on an InP substrate by molecular beam epitaxy at a substrate temperature of 200–240°C; it was characterized by high-resolution X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The XRD results indicated deterioration of crystalline quality at a growth temperature between 200–220°C, and a transformation of excess As in the crystal of LTG In0.45Ga0.55As into As precipitates by thermal annealing. The RBS for LTG In0.45Ga0.55As grown at 220°C indicated that the In atoms were located in interstitial sites along the [110] direction. The ratio of the interstitial In atoms was estimated to be almost 40% of all In atoms in the LTG In0.45Ga0.55As, and this ratio did not change abruptly after annealing to 550°C.