Material issues in AlGaInP red-emitting laser diodes

Red-emitting AlGaInP quantum well lasers are now a well-established commercial product with a range of applications, many in high-volume, low-cost market sectors. Although the operation of these devices is generally understood, there are a number of critical aspects of the device structure, determined by the crystal growth process, which have an influence on key performance characteristics. A number of these are considered in this paper, particularly strain limits and non-planar growth, the effect of interface roughness on optimisation of the well width for minimum threshold current, and the influence of the doping density of the p-cladding layer on the temperature sensitivity of threshold current. These factors are examined in terms of the mechanisms by which they affect the operation of the device.