Field-dependent nonlinear luminescence response of (In,Ga)N/GaN quantum wells

We have investigated the electric-field- and excitation-density-induced variation of the optical transition energy and cathodoluminescence (CL) as well as photoluminescence intensity of a single (In,Ga)N/GaN quantum well deposited in the depletion region of a p-n junction. The electric-field dependence of the transition energy is significantly influenced by field screening in the depletion region due to the excited carriers and by filling of band tail states of localized excitons. The electric-field dependence of the CL intensity is characterized by an abrupt and strong quenching mainly due to drift of excited carriers in the depletion region. A gradual screening of the p-n junction field with increasing excitation density causes a strongly nonlinear CL response. We describe this nonlinear behavior theoretically by a rate equation model.