Influence of Surface Step Density on the Growth of Mercury Cadmium Telluride by Molecular Beam Epitaxy

Abstract

ABSTRACTWe report for the first time the results of structural and optical characterizations performed on Mercury Cadmium Telluride (MCT) grown simultaneously by Molecular Beam Epitaxy (MBE) on (11 1)B 4°misoriented and (211)B CdZnTe substrates. These two Te-terminated surfaces differ only by the density and the nature of their surface steps. In MBE conditions we do not observe any difference of incorporation between the two orientations at low growth temperatures and only a slight difference in Te and Hg incorporations above 200°C. This study confirms that the growth mode is essentially the same on both orientations and the growth proceeds by step-flow. The higher step density on (211) surfaces allows broader tolerances on the substrate temperature for the growth of twin-free material. It also leads to higher crystalline quality for the lowest temperatures. These observations have been confirmed by magneto-absorption experiments on superlattices grown simultaneously on both orientations.