Carrier Dynamics of Deep-Level States in InGaN/GaN Multiquantum Wells

Abstract

InGaN/GaN (3nm/10nm) multiquantum wells (MQWs) were grown on (0001) sapphire substrates by metal-organic chemical vapor deposition. To characterize the effect of internal electric fields on deep-level states in InGaN MQWs, deep-level transient spectroscopy (DLTS) and bias-dependent photoluminescence (PL) measurements were performed. The thermal activation energy of MQWs obtained from DLTS spectra decreased to 0.15 eV with an increase in reverse measure bias from -2 to -10 V, which indicates partially cancelled internal fields. The blue shift of PL peak energy was about 0.05 eV when the reverse measure bias was changed from 0 to -5 V. This is explained well by carrier dynamics in the conduction band of InGaN/GaN MQWs, which affects carrier recombination energies corresponding to the band edge to edge transitions with changing reverse measure bias.