Dislocation density variations in HgCdTe films grown by dipping liquid phase epitaxy: Effects on metal–insulator–semiconductor properties

Abstract

The dislocation density variations in HgCdTe films grown by liquid phase epitaxy (LPE) from tellurium-rich melts were measured and were found to depend on film growth temperature, substrate dislocation density, epitaxial film thickness, and postgrowth annealing in Hg vapor. Thin films, less than about 30–40 μm in thickness, exhibit dislocation densities which generally follow the dislocation densities of the substrates. In thicker epitaxial films, however, dislocation multiplication can accompany Te precipitation and subsequent low temperature annealing in Hg vapor, thereby, raising the density of dislocations by as much as a factor of 3–10. Use of a high temperature preanneal in Hg vapor can be employed to eliminate dislocation multiplication during low temperature annealing. When this preanneal is used in conjunction with very thick film growth with thicknesses greater than about 80 μm, dislocation densities in the LPE films can fall to values below those in the substrate. The dependence of metal–insulator–semiconductor storage times on dislocation densities in these films has also been measured.