MOVPE GROWTH AND CHARACTERIZATION OF HG0.7CD0.3TE LAYERS

The MOVPE growth of Hg0.7Cd0.3Te(MCT) layers is described. On 2 inch GaAs substrates, a graded composition buffer layer together with growth interruptions during the IMP deposition is found to reduce the density of pyramidal defects. It is found from SIMS measurements that Ga is transported from the GaAs substrates via the vapour phase into the layers. Lamella twins parallel to the surface, in (111) MCT layers grown on (100) GaAs substrates, are found to initiate electrically active centers. Carrier concentrations and mobilities comparable to those reported so far, whatever the growth technique used, are found from electrical measurements: ni {reversed tilde equals} 1016 cm-3 with μ300K{reversed tilde equals} 104 cm2/V·s,n77Klying between 3×1014 and 2×1015 cm-3 with μ77K in the (2-12)×104cm4/V·s range. A uniformity of ±0.01 mol over large areas of {reversed tilde equals} 10 cm2 is found from FTIR spectrometry. Photoconductors have been made from these layers, with performances comparable to those of bulk crystal devices. © 1989.