Excitation-intensity and temperature dependences of photoluminescence in ZnMgO film

Photoluminescence (PL) properties of Zn0.8Mg0.2O film are investigated under high excitation and low temperature. With increasing excitation intensity, emission from the inelastic exciton-exciton scattering gradually dominates, meanwhile the bound exciton emission decreases. The exciton binding energy is estimated to be similar to 110-128 meV from the energy of P-band and PL thermal quenching, much higher than that of bulk ZnO. Temperature-dependent PL spectra reveal a room temperature internal quantum efficiency of 9.2% under high excitation, suggesting a high optical quality of the Zn0.8Mg0.2O film.