Surface photovoltage spectroscopy characterization of InGaPN alloys grown on GaP substrates

In 0.176 Ga 0.824 P 1− y N y ( y = 1.5 %– 8.7%) alloys grown on GaP(001) substrates via metalorganic vapour phase epitaxy were characterized by surface photovoltage spectroscopy (SPS) in the temperature range between 125 and 400 K. The band gap energies are determined and their temperature dependences are analysed by Varshni and Bose–Einstein expressions. The parameters that describe the temperature variations of the band gap energies are evaluated and discussed. The surface photovoltage spectra also revealed that a transition from indirect to direct band gap is taking place for the N-incorporated samples and the quadratic correction for the band gap bowing is only applicable for low nitrogen containing samples.