Non-radiative recombination centers in AlGaN quantum well characterized by two-wavelength excited photoluminescence

Two-wavelength excited photoluminescence, a non-destructive and non-contacting method for defect study has been used to investigate the AlGaN multiple quantum well (MQW) emitting at ~260 nm. We have succeeded to detect the non-radiative recombination (NRR) centers in both wells and barrier layers using a below-gap ex- citation (BGE) light of 1.17 eV. The PL intensity of both well and barrier layers decreases after irradiation of BGE which can be explained by the well-established two-level model. The normalized PL intensity decreases with increasing BGE power density for both cases but more pronounced for the barrier layer. The normalized PL intensity increases for both well and barrier layer's emission with increasing AGE density and becomes saturated at higher excitation due to the fill-up of NRR centers.