Radiative and Auger recombination processes in indium nitride

Abstract

InN and In-rich InGaN alloys emit in the infrared range desirable for telecommunication applications. However, the droop problem reduces their efficiency at high power. Nonradiative Auger recombination is a strong contributor to this efficiency loss. Here, we investigate radiative and Auger recombination in InN and In-rich InGaN with first-principles calculations. We find that the direct eeh process dominates Auger recombination in these materials. In the degenerate carrier regime, the Auger and radiative rates are suppressed by different mechanisms: the radiative rate is affected by phase-space filling while Auger recombination is primarily reduced by free-carrier screening. The suppression of the radiative rate onsets at lower carrier densities than that of the Auger rate, which reduces the internal quantum efficiency of InN devices. Droop in InN can be mitigated by increasing the bandgap through alloying with GaN. We demonstrate that the peak efficiency of In0.93Ga0.07N alloys (which emit at 1550 nm) is 33% higher than that of InN and occurs at higher carrier densities.