Influence of Si doping on optical properties of cubic GaN grown on GaAs (001) substrates by metalorganic vapor phase epitaxy

Si-doped cubic GaN films with different Si concentrations ranging from 1 x 10(16) to 1 x 10(20) cm(-3) were grown on GaAs (001) substrates by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). The Si concentrations in our samples were determined by secondary ion mass spectroscopy (SIMS). The samples were evaluated by low temperature photoluminescence (PL). The excitonic transition dominated the PL spectra for all the samples, indicating that Si-doped cubic GaN films with high optical quality have been obtained. A clear peak shift to shorter wavelength because of Si doping was observed for excitonic and donor acceptor (DA) pair transitions, respectively. Due to the random distribution of donor impurities, a broadening of the luminescence linewidth was also observed. The luminescence intensity of these two peaks increases as the Si concentration is increased, showing that nonradiative transitions dominate at low doping level.