METALORGANIC VAPOR-PHASE EPITAXY GROWTH OF INPASSB ALLOYS LATTICE-MATCHED TO INAS

A range of InPAsSb quaternary alloys representative of the full span o f InAs latticed matched compositions have been grown by metalorganic v apour phase epitaxy (MOVPE). The epilayers had good morphology, good c rystallinity by X-ray, and low impurity content. In low temperature ph otoluminescence measurements, all the compositions containing less tha n 70% InAs exhibited anomalous spectra with low intensity peaks at wav elengths which were longer than predicted theoretically. The reason wa s identified by transmission electron microscopy as micro-scale compos ition fluctuations which increased in strength as the InAs content was reduced. This phenomenon, caused by growth of compositions within a m iscibility gap, prevented InPAsSb alloys grown by conventional MOVPE b eing used to produce high efficiency lasers in the 2-3 mu m band.