Effect of process conditions on the quality of CdTe grown on InSb by organometallic epitaxy

The morphology and crystal quality of CdTe grown on InSb substrates are shown to be critically dependent on the pregrowth stabilization procedure to which the substrate has been subjected. It is shown that layer growth on a dimethylcadmium stabilized InSb substrate results in CdTe layers with a large number of hillocks whereas growth on a diethyltelluride stabilized substrate results in a smooth morphology. These hillocks are initiated by the reaction of dimethylcadmium with the InSb surface; alloys of In-Cd-Sb formed at the interface result in deterioration of the layer morphology. This problem can be avoided by growth on a diethyltelluride stabilized surface, at temperatures below 400 °C. Improvement in the layer quality by use of this technique is illustrated by a study of the photoluminescence spectra (PL) of CdTe grown by these two methods. Layers have been grown with a band-edge PL peak having a full width half-maximum of 2.1 meV at 12 K. To our knowledge, this is the lowest value for epitaxial layers of CdTe on InSb grown by any technique at the present time.