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

GaP/AlP short period superlattices (SLs) are grown on GaP substrates b y gas source molecular beam epitaxy (MBE). Strong photoluminescence is observed in the green-to-yellow wavelength range at 4.2 K. Photolumin escence and electroreflectance spectra are in good agreement with the theoretical predictions for the formation of the zone-folded direct ba nd gap. The refractive indices of the SLs are larger than those of bul k 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 enh anced epitaxy.