Kinetics of molecular‐beam epitaxial HgCdTe growth

Abstract

The surface kinetics that govern molecular‐beam epitaxial (MBE) growth of HgCdTe films places strict boundaries on the optimal deposition conditions to be selected. This paper will examine the limits imposed by the surface kinetics on the Hg flux, substrate orientation, and substrate temperature to be chosen for MBE HgCdTe film growth. The range of Hg flux available to grow single crystalline HgCdTe (as determined by reflection high‐energy electron diffraction) will be seen to vary significantly with the (112)Te, (112)Cd, and (001) growth orientations. The HgCdTe(112)Te films are deposited with a high Hg condensation coefficient at 200 °C (0.04–0.10), have an excellent surface morphology, and avoid the cellular twins that are found in HgCdTe(111)Te layers. However, each of the three orientations result in faceted growth at substrate temperatures near 200 °C; at this substrate temperature, HgTe begins to desorb from the growth surface which leads to a preferential exposure of the lower energy (111) planes. Due to the variation in the HgTe growth rate with facet orientation, the HgCdTe films grown near 200 °C are found to have significant lateral compositional inhomogeneities.