GAS-SOURCE MOLECULAR-BEAM EPITAXY GROWTH OF GAP/ALP SHORT-PERIOD SUPERLATTICES

GaP/AlP short period superlattices (SLs) are grown on GaP substrates by gas source molecular beam epitaxy (MBE). Strong photoluminescence is observed in the green-to-yellow wavelength range at 4.2 K. Photoluminescence and electroreflectance spectra are in good agreement with the theoretical predictions for the formation of the zone-folded direct band gap. The refractive indices of the SLs are larger than those of bulk GaP, AlP and AlGaP, indicating the possibility of formation of laser diode structures using GaP/AlP SL as an active layer. By using Be as a p-type dopant source, a hole concentration of as high as 1.5 X 10(19) CM-3 is easily obtained in GaP. It is also shown that the interface and optical properties of SLs are improved by gas source migration enhanced epitaxy.