Internal Quantum Efficiency

Abstract

In the first part, we have introduced experimental results of the internal quantum efficiency (IQE) droop depending on temperature in both the electroluminescence and the resonant photoluminescence. The IQE droop mechanisms ever reported have been reviewed. An inherent origin of the efficiency droop has been suggested as the saturation of the radiative recombination rate in the InGaN quantum well at low current and subsequent increase in the nonradiative recombination rates at high current. The degree of saturation is determined by operating temperature and effective active volume. Although the saturation of the radiative recombination rate is common origin of the IQE droop, the shapes of the IQE versus current, i.e. the IQE droop curve, vary with the dominant nonradiative recombination process. In the second part, we have reviewed the IQE measurement methods theoretically as well as experimentally. A simple IQE estimation method based on the constant ABC model in the carrier rate equation is introduced in terms of its convenience and application limitation. Other methods have been also reviewed by focusing on all-optical methods such as the temperature-dependent photoluminescence (TDPL) and the temperature-dependent time-resolved photoluminescence (TD-TRPL) methods.