On the Monte Carlo Description of Hot Carrier Effects and Device Characteristics of III-N LEDs

Our paper just appeared in Advanced Electronic Materials (Adv. Electron. Mater. 2017, 1600494).

We developed fully self-consistent Monte Carlo (MC) simulations to investigate the effects of hot carriers in the operation of group III nitride (III-N) light-emittingdiodes (LEDs) and to outline the shortcomings of the drift-diffusion (DD) models in modeling multiquantum well (MQW) LEDs. Recent experiments have suggested that high energy charge carriers can have a significant effect on device operation, possibly playing an important role in the efficiency droop. As hot carriers are not accounted for by device simulation tools based on DD and quasiequilibrium conditions, more advanced tools are needed. Our MC simulation results show that hot carrier transport can lead to substantial electron overflow distributing the carriers more evenly in MQW structures, increasing the total recombination and leakage currents. Also Auger recombination is found to drive the distributions out of quasiequilibrium but, surprisingly, it does not contribute extensively to the leakage current. The simulations involve in-house ab-initio band structures as well as parameterized band structures, but qualitatively the results do not strongly depend on the band structure details. However, there is a clear discrepancy between the DD and MC simulations at bias voltages significantly exceeding the built-in potential when the LED consists of several deep quantum wells.