PHOTOLUMINESCENCE OF GAAS-LAYERS HYBRID-GROWN ON SI BY MBE AND LPE

We have found extraordinary photoluminescence (PL) for GaAs layers grown on Si substrates by the MBE-LPE hybrid method, which is molecular beam epitaxy (MBE) combined with subsequent liquid phase epitaxy (LPE). The PL spectra showed only one broad peak with a large red-shift (44-98 meV) and large intensity compared with the exciton peak of an MBE-grown sample. The red-shift increased with raising the growth temperature of LPE for the hybrid growth. Si impurities unintentionally incorporated into the MBE-grown region as well as the LPE-grown region of the hybrid-grown GaAs layers were observed by SIMS measurements. The PL peaks with large red-shift of the hybrid-grown layers were considered to arise from a formation of additional energy levels in the band structure due to the compensated Si impurities in the LPE-grown region.