Growth temperature dependence of GaS thin films on GaAs (001) surface

The growth of GaS films on GaAs(001) surfaces by using thermal evaporation of layered-compound GaS has been investigated by Auger electron spectroscop y, low-energy electron-loss spectroscopy (LEELS), x-ray photoemission spect roscopy (XPS), and atomic force microscopy (AFM) as a function of depositio n temperature. The LEELS spectrum of the films grown at lower temperatures (less than or equal to 400 degrees C) resembles that of a GaS single crysta l, whereas that of the films grown at 450 degrees C reveals that GaAs surfa ce was terminated by Ga2S3 layer. XPS spectra suggest that after annealing at 500 degrees C, S atoms moved from As atoms to Ga atoms to form stable Ga -S bonds at the interface and As-S bonds are observed to be less stable. Th e band discontinuity at the GaS/GaAs(001) interface estimated by XPS showed the straddling-type I band alignment. Surface morphology of the films stud ied by AFM reveals the layer-by-layer initial growth of GaS. (C) 1999 Ameri can Institute of Physics. [S0021-8979(99)04008-6].