Modeling multiple quantum barrier effects and reduced electron leakage in red-emitting laser diodes

Abstract

Severe electron leakage impedes the full exploitation of AlGaInP laser diodes in the 630nm regime. Such thermally activated currents are attributed to inherently small conduction band offsets and intervalley transfer between the Γ and X conduction band minima. To negate the detrimental effect of these two intrinsic material issues a theoretical model is proposed. A multi-quantum-barrier (MQB) structure able to inhibit both Γ- and X-band transmissions is inserted in the p-doped region adjacent to the active region of the device, allowing a greater percentage of injected electrons to be reflected back within the active region. The design of the MQB follows a strict optimization procedure that takes into account fluctuations of superlattice layer width and composition. This model is used in conjunction with a dual conduction band drift-diffusion simulator to enable the design of the MQB at an operating voltage and hence account for nonlinear charge distribution across it. Initial results indicate strong agreement between experimentally determined effective enhancements and those predicted theoretically.