EFFECTS OF HIGH-TEMPERATURE ANNEALING ON THE STRUCTURAL AND CRYSTALLINE QUALITIES OF GAAS HETEROEPITAXIAL LAYERS GROWN ON SI SUBSTRATES USING 2-STEP AND DIRECT-METHODS BY MOLECULAR-BEAM EPITAXY

The structural and crystalline qualities of GaAs/Si heteroepitaxial la yers (heteroepilayers) were remarkably improved by annealing at temper atures above 900 degrees C, independently of the growth methods, eithe r two-step or direct. The effects of high-temperature annealing on the optical property, residual strain, and the relation of the improvemen t in the quality with the out-diffusion of Si from the substrates and with vacancies in the GaAs heteroepilayers have been systematically in vestigated by a series of measurements using photoluminescence spectro scopy, secondary-electron microscopy, double-crystal X-ray diffraction , secondary-ion mass spectroscopy and cross-sectional transmission ele ctron microscopy.