Temperature dependence of nonradiative recombination processes in UV-B AlGaN quantum well revealed by below-gap excitation light

Nonradiative recombination (NRR) processes through defect states and their temperature dependence in UV-B AlGaN MQW sample on sapphire substrate grown by MOCVD technique have been studied by photoluminescence (PL) spectroscopy. We detected NRR centers by adding a below-gap excitation light with photon energies from 0.93 eV to 1.46 eV on an above-gap excitation light of 4.66 eV. All the BGE energies decreased PL intensity at 25 K, and the most-distinct quenching is observed by 1.27 eV BGE at the same BGE photon number density. The temperature-dependent PL intensity for the BGE energy of 1.27 eV is interpreted by three NRR centers. The one-level model dominates over that of two-level model in the temperature range 58 K < T < 88 K. The two-level model prevails in other region of temperature. The combination of one-level and two-level models is consistent with the spectral peak-energy shift as a function of temperature.