Characterization of mercury cadmium telluride epitaxial films by high resolution X-ray diffraction experiments

High resolution X-ray diffraction techniques were employed for characterization of 20 μm thick mercury cadmium telluride ( MCT) epitaxial films grown by liquid phase epitaxy on Imm thick (111) CdTe wafers. Diffraction experiments were performed with (111) planes which are parallel to the larger surfaces of the specimen crystal as well as with (220) planes which are perpendicular to the surface. In the experiments with (220) planes, the specimens were oriented for diffraction from an edge.Two radiations: MoKα 1 and CuKα 1 were employed. It was observed that there is a large variation in the level of perfection of substrate crystals with diffraction curve half widths for (111) diffracting planes in the range: 10 arc sec [ MoKα 1 ;(+,-,+) geometry ] to 100 arc sec [ CuKα 1 ;(+,-) geometry ]. Deposition of epitaxial films produced significant broadening of diffraction curves of even the nearly perfect substrates. The nearly perfect substrate showed interesting results when experiments were performed with the cleaved surface along (220) planes (edge).