Molecular beam epitaxial growth of (100) Hg0.8Cd0.2Te on Cd0.96Zn0.04Te

Abstract

The molecular beam epitaxial growth of (100) Hg0.8Cd0.2Te epilayers has been systematically investigated in order to optimize the growth parameters and in particular the Hg/Te flux ratio. Both the pyramidal hillock density and the mobility depend on the Hg/Te flux ratio. A minimum in the hillock density correlates well with the largest mobilities. As is well known, electrical properties are strongly influenced by structural defects. Structural defects due to non-stoichiometry, i.e. vacancies and antisites, can be largely reduced by optimizing the Hg/Te flux ratio. It is shown that an optimum Hg/Te flux ratio exists within a narrow range between 270 and 360 at the growth temperature of 180 degrees C, in contrast with the larger range of the Hg/Te flux ratio over which single-crystal growth could be maintained. The x values of the Hg1-xCdxTe epilayers were determined from the E0 gap dependence as well as from the E1 gap dependence. The difficulties encountered in determining the x value from normal transmission curves, i.e. from E0(x), due to the Burstein-Moss shift are discussed.