ZnSSe epilayers with extremely low defect density by the growth-temperature optimization

Abstract

In order to realize ZnSSe/GaAs heteroepitaxial layers with lower defect density, we have introduced molecular beam epitaxy growth by a three-step temperature correction which takes account of the cell radiation and surface emissivity effects superposed on the Fabry-Perot interference oscillation in the pyrometric temperature. The optimum correction rates of growth temperature are determined by the analysis of double-crystal x-ray rocking curves, and an empirical profile for the control temperature as a function of growth time is proposed for the optimum ZnSSe growth. While the etch pit density is ≤ 8 × 10 4 cm −2 in normal molecular beam epitaxy growth, an etch pit density of ≤ 5 × 10 3 cm −2 , which is the lowest value known so far, is realized in ZnSSe/GaAs(100) epilayers grown by using the linearly corrected profile.