Method of synthesizing thin, single crystal layers of silver thiogallate

Abstract

A method of growing a single crystal layer of silver thiogallate having a maximum thickness of 50 micrometers. This crystal is of a high purity having a higher degree of crystalline perfection than the substrate on which it is grown. The crystal is grown epitaxially from a solution of silver thiogallate in a solvent of either antimony sulfide or lead sulfide. The solution is prepared by heating a mixture of the materials (solid silver thiogallate in molten solvent) slowly at a rate of, for example, 3.degree. to 5.degree. C. per minute until the mixture reaches a temperature about 10.degree. C. above the liquidus, and maintaining this temperature for 16 hours or more. The above referenced solution is then gradually cooled at a rate of, for example, 1.degree. C. per minute to the temperature at which crystal growth is to be initiated. At this temperature a polished single crystal substrate of a material which has an appropriate lattice relationship with silver thiogallate is dipped into the molten solution. The solution and substrate are then cooled at a slow rate of, for example, 0.05.degree. C. per minute over the temperature range within which crystal growth is to occur. During this cooling, the substrate is rotated in the melt. On obtaining the desired thickness of the epitaxially-grown single crystal layer, the substrate is withdrawn from the solution.