Trap-assisted tunneling as possible carrier escape mechanism in InGaN/GaN light-emitting diodes

Carrier escape has been widely observed in light-emitting diodes (LEDs) and it is crucial to the performance of quantum-well photovoltaic and photodetector devices. However, the mechanisms proposed thus far, including thermionic emission and direct tunneling, fail to explain the experimental results. In this work, a simplified trap-assisted tunneling model that considers the energy distribution on trap states is established through which experiment results can be explained reasonably. The nonuniform distribution of diffused p-type dopants is proposed as the reason for the abnormal voltage-dependent and excitation-energy-dependent photocurrent experimental results through energy band diagram simulation.