Study of band-gap narrowing effect and nonradiative recombination centers for heavily C-doped GaAs by photoluminescence spectroscopy

The band-gap narrowing effect of GaAs as a function of carbon doping concentration has been measured using photoluminescence (PL) spectroscopy on samples grown by metalorganic chemical-vapor deposition. The range of carbon concentration varies from 3.4×1018 to 1.1×1020 cm−3. The experimental results obtained from PL spectra taking tailing effects into account are in good agreement with recent theoretical calculations. The intensity of PL spectra decreases rapidly when the free-carrier concentration is higher than about 4×1019 cm−3. This phenomenon cannot be explained with only the varying tendency of the minority-electron lifetime of the radiative recombination process, indicating the introduction of additional nonradiative recombination centers in heavily C-doped GaAs.