Liquid phase epitaxy of mercury cadmium telluride layer

The specification discloses a process and apparatus for forming a layer of mercury cadmium telluride of predetermined composition on the surface of a selected substrate by first providing a crystal growth melt comprising mercury, cadmium, and tellurium in a vertically-oriented crystal growth chamber. The melt comprises 33.33 mole percent or more of mercury and is maintained at a predetermined temperature above the liquidus temperature thereof. A condensing means is provided atop the crystal growth chamber in order to condense vapors of mercury which escape from the melt and to return this condensed mercury to the melt, to thereby maintain the melt at a constant composition. The substrate is contacted with this crystal growth melt for a predetermined period of time while cooling the melt below its liquidus temperature at a predetermined rate sufficient to cause the crystal growth of the layer of mercury cadmium telluride on the substrate to a desired thickness. The layer of mercury cadmium telluride so formed is of uniform composition and of high purity and is formed at a relatively low growth temperature and relatively low system pressure.