Abstract: Disclosed is a multilayer electro-optical material having a plurality of adjacent, single crystals wherein each crystal layer has different electrical and optical properties from its adjacent layer or layers. This material is made by a method wherein the successive layers are epitaxially grown from a molten solution of said electro-optical material optionally containing at least one dopant. In one embodiment, such electro-optic material comprises silver thiogallate, wherein successive epitaxial layers are grown from a molten solution of silver thiogallate and potassium chloride, and which optionally includes at least one dopant. This molten solution exhibits the characteristic that, for any specific solution composition, layers having different electrical and optical properties can be obtained by cooling over the temperature range which will yield crystal growth of the composition corresponding to the desired electrical and optical properties.

Abstract: A method of making a thin, high purity single crystal layer of silver thiogallate. According to the preferred embodiment of this method, a seed crystal substrate of silver thiogallate is dipped into a molten solution of silver thiogallate dissolved in potassium chloride. Upon slowly cooling the solution, the thin layer of single crystal silver thiogallate forms on the substrate. Upon removal, very little of the potassium chloride adheres to the surface, and what does adhere to the surface can be easily removed by washing the surface with hot water.

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.