CHARACTERIZATION AND IMPROVEMENT OF GAAS-LAYERS GROWN ON SI USING AN ULTRATHIN A-SI FILM AS A BUFFER LAYER

GaAs epilayers grown on Si by metalorganic chemical vapor deposition ( MOCVD) using an ultrathin a-Si buffer layer were characterized by deep -level transient spectroscopy (DLTS). Six electron traps with activati on energies of 0.79, 0.67, 0.61, 0.55, 0.53 and 0.32 eV below the cond uction band were determined by fitting the experimental spectra. Two o f the levels, C (0.61 eV) and F (0.32 eV), were first detected in GaAs epilayers on Si and identified as the metastable defects M3 and M4, r espectively. In order to improve the quality of GaAs/Si epilayers, ano ther GaAs layer was grown on the GaAs/Si epilayers grown using MOCVD. The deep levels in this regrown GaAs epilayer were also studied using DLTS. Only the EL2 level was found in the regrown GaAs epilayers. Thes e results show that the quality of the GaAs epilayer was greatly impro ved by applying this growth process.