NEAR-BAND-EDGE PHOTOLUMINESCENCE OF GAAS EPITAXIAL LAYERS GROWN AT LOW-TEMPERATURE

Photoluminescence and reflectance spectra in a near-band-edge region h ave been measured for homo-epitaxial GaAs layers grown at low temperat ure (LT-GaAs layers; temperatures from 200 to 265 degrees C). It is fo und that the photoluminescence spectrum depends strongly on the growth conditions. A narrow hole (dip) is observed in the emission band for samples prepared under certain growth conditions. The dependence of th e dip profile on the ambient temperature, excitation power, excitation energy and growth conditions has been studied in detail. The spectral hole is attributed to the free exciton absorption in the top layer fo r luminescent Light emitted from the underlying layer of LT-GaAs. The experimental results show that the spectral profile of the photolumine scence reflects the crystal quality and microstructure of the LT-GaAs layers.