Compositional Variation Related to the Growth Process in GaAIAs Epitaxial Layers

Compositional profiles of epitaxial GaA1As layers grown by liquid phase epitaxy using the supersaturation technique were investigated in relation to the growth conditions by laser Raman spectroscopy. In the diffusion limited process with a flat temperature profile during epitaxial growth cycle, a uniform layer of 1.26 • 0.017 ~m (_+ 1.3%) with a small composi-tional variation of 0.457 • 0.007 ( • 1.5%) can be accomplished. On the other hand, remarkable compositional variations (> • 10%) occur during an initial growth stage, which depends on the initial supersaturation. Compositional uniformity is improved to 0.152 • 0.007 ( • 4.6%) by decreas ing initial supersaturat ion to 2.5~ III-V compound GaA1As grown on GaAs substrates has received much attention as a material for optoelectronic devices uch as laser diodes and light emitting diodes (1-4). In the device application of heterostructures, two of the most important properties are uniformity of composition and layer thickness over the whole surface of a substrate. Several authors studied the compositional inhomogene-ity of GaA1As epitaxial layers grown by liquid phase epi