The In0.2Ga0.8As layers were grown onto GaAs substrates with graded buffer layers by metalorganic vapor phase epitaxy at 370 to 630C. Good surface morphology with a cross-hatch pattern was obtained at 600 and 630C. Transmission electron microscopy observation confirmed that the cap layers had a threading dislocation density of between 1.3 and 2.0 x 106/cm2. At 500C, a layer showed a rough surface morphology. Phase separation was revealed by transmission electron microscopy. The threading dislocation density was over 107/cm2 at 500C. Good surface morphology with a cross-hatch pattern was obtained at 430, 450 and 480C. A layer grown at 430C showed the lowest threading dislocation density of 2.5 x 105/cm2. Low temperature growth was effective in lowering the threading dislocation density in the cap layers.

Temperature Dependence of Threading Dislocation Density in In0.2Ga0.8As Layers Grown on GaAs Substrates by Metalorganic-Vapor Phase Epitaxy. Y.Takano, K.Kobayashi, S.Shirakata, M.Umezawa, S.Fuke: Journal of Crystal Growth, 2005, 282[1-2], 36-44