Reduction of the Dislocation Density in GaAs1 − x Sb x Layer on GaAs Grown by an Improved LPE Method

Abstract

An improved LPE method in which the solid surface is always covered by a solution during step-graded growth of GaAsl-xSbx on GaAs substrates produces etch pit densities of 3-6 • 10 ~ cm -2. In contrast, layers grown by conventional step or continuously graded LPE have EPD of 6 X 108-2 X 10 ~ cm -2. The composition of the top layer is approximately GaAso.pSbo.1 in all cases. The reduction of EPD by the improved LPE method is attributed to limiting the nucleation of small islands to the first buffer layer, under the conditions that the grown surface is always covered by the solution subsequent to the growth of the first buffer layer.