Study of charge relaxation processes in quantum wells of InGaN/GaN MQW LEDs using frequency dependences of capacitance and conductance

Capacitance-frequency and conductance-frequency dependences for InGaN/GaN multiple-quantum-well light-emitting structures are investigated at wide ranges of temperature and bias voltage. The charge relaxation in a quantum well is found to be satisfactorily described by two emission processes with different dependences of emission rate on temperature. It is shown that in typical InGaN/GaN light-emitting structures, one or a few quantum wells can be filled with electrons even for the relatively high reverse biases applied to the structure and contribute to the measured capacitance. This allows to explain the observed temperature and frequency dependences of apparent carrier concentration profiles obtained under capacitance—voltage profiling in these structures.