Crystalline perfection in GaInAsP/GaAs laser structures with GaInP or AlGaAs cladding layers

The crystalline perfection of GaInAsP layers grown lattice-matched to GaAs by metal-organic vapour phase epitaxy (MOVPE) has been studied using cathodoluminescence (CL) and transmission electron microscopy (TEM). The tendency for phase separation observed for single layers with composition close to the miscibility gap is further enhanced in broad-area laser diodes, where even GaInAs grown on top of a decomposed layer can show decomposition. The crystalline perfection of the layer structure is correlated to the optoelectronic properties of the laser diodes. For buried laser structures, the presence of different growth facets leads to additional problems due to composition fluctuations that can result in defect formation when GaInAsP is used for the regrowth.