Kinetics of persistent photoconductivity in InGaN epitaxial films grown by MOCVD

In this study, the spectral and temperature dependence of persistent photoconductivity (PPC) in InGaN, which was grown by metal-organic chemical vapor deposition (MOCVD), were discussed. The related optical and electrical properties of the InGaN epilayers have been investigated by PPC and photoluminescence (PL). The metastability was observed in InGaN epilayers with indium contents of 0.12 and 0.2, and show that the PPC effect arises from alloy potential fluctuations in InGaN layer. PPC decay behavior can be well described by a stretched-exponential function and the relaxation time constant τ and decay exponent β both increase with increasing In content. Moreover, the carrier capture energy barrier for free carrier capture by defects ΔE was found to increase with the increase of indium concentration as well. All these observations show clearly a relation between localized exciton in InGaN-based optoelectronic devices, and the deep levels significantly influence the carrier lifetime of minority carrier devices.