Band gap narrowing effects in carbon doped GaAs by photoluminescence spectroscopy

The effects of band gap narrowing in carbon-doped GaAs epilayers have investigated as a function of substrate orientation, temperature and hole concentration by using photoluminescence (PL) spectroscopy. The band gap energy of the epilayers shows a strong dependence on the substrate orientation. This can be explained by the difference of the carbon doping concentration at each substrate orientation rather than the lattice mismatch between the carbon-doped epilayers and GaAs substrate. The temperature dependence of the band gap energy is well expressed by the Varshni equation. The band gap narrowing as a function of hole concentration is measured and compared with the previously reported results.