Lateral carrier confinement and threshold current reduction in InGaN QW lasers with deeply etched mesa

Shallow etch depths may contribute to a reduction in the optical gain of multiple quantum well (MQW) lasers through the lateral diffusion of carriers away from the region of greatest optical intensity. Deeply etched mesas can prevent this lateral diffusion, but this practice may itself contribute to a degradation of optical gain if the sidewalls are not effectively passivated. Simulation results considering the effects of surface recombination velocity (SRV) at the edge of etched active layers indicate that SRV must be reduced below approximately 105cm/s in order for deep etch designs to provide benefit. Very few experimental studies quantify the efficiency of GaN surface passivation in terms of SRV. Further experimental studies are required to better assess the viability of deep etch MQW laser designs.