Process for making mercury cadmium telluride

Claim 2

The process for forming mercury cadmium telluride which comprises forming an atmosphere of mercury vapor from liquid mercury having a desired temperature between about 25° C. and 350° C. while maintaining the liquid mercury temperature within about 1° C. of the desired temperature and contacting the mercury vapor with a growth solution consisting of mercury, cadmium, and tellurium having a desired temperature between about 425° C. and 550° C. and maintaining the growth solution temperature within about 1° C. of the desired temperature.

Claim 3

The process for forming a substrate-epilayer composite having an epitaxial layer of mercury cadmium telluride which comprises forming an atmosphere of vaporous mercury from liquid mercury, having a desired temperature between about 25° C. and 350° C. while maintaining the liquid mercury within about 1° C. of the desired temperature and contacting said mercury vapor with a growth solution consisting of mercury, cadmium and tellurium having a desired temperature between about 425° C. and 550° C. and maintaining the growth solution temperature within about 1° C. of the desired temperature to form a compositionally controlled solution of mercury-cadmium-tellurium and contacting the solution of mercury-cadmium-tellurium with a substrate to form an epitaxial layer of mercury cadmium telluride on said substrate.

Claim 4

The process for forming a substrate-epilayer composite having an epitaxial layer of mercury cadmium telluride which comprises forming an atmosphere of vaporous mercury from liquid mercury, having a desired temperature between about 25° C. and 350° C. while maintaining the liquid mercury within about 1° C. of the desired temperature and contacting said mercury vapor with a growth solution consisting of mercury, cadmium and tellurium having a desired temperature between about 425° C. and 550° C. and maintaining the growth solution temperature within about 1° C. of the desired temperature to form a compositionally controlled solution of mercury-cadmium-tellurium and contacting the solution of mercury-cadmium-tellurium with a substrate to form an epitaxial layer of mercury cadmium telluride on said substrate.

Claim 5

The process of claim 1 wherein the liquid mercury is maintained within about 0.2° C. of the desired liquid mercury temperature.

Claim 6

The process of claim 2 wherein the liquid mercury is maintained within about 0.2° C. of the desired liquid mercury temperature.

Claim 7

The process of any one of claims 1, 2, 3 or 4 wherein the growth solution is maintained within 0.2° C. of the desired temperature.

Claim 8

A process for preparing epitaxial layers of Hg 1-x Cd x Te on suitable substrates comprising the steps of: (a) placing an initial source material selected from the group consisting of tellurium, a mixture of mercury and tellurium or a mixture of mercury, tellurium and cadmium in a growth bin and a CdTe source wafer and substrate wafer in a slider insert; (b) heating the initial source material, source wafer and substrate wafer to a temperature at which simultaneously heated Hg in a boat produces a mercury vapor pressure over the source material and within time converts the initial source material to a solution material of mercury-tellurium or mercury-cadmium-tellurium; (c) sliding the CdTe source wafer so that contact is made with the solution for a period of time; (d) further sliding the CdTe source wafer so that contact is no longer made with the solution; (e) sliding the CdTe substrate wafer so that contact is made with the solution for a period of time sufficient to produce a desired thickness of epitaxial layer of HgCdTe on the CdTe substrate; (f) further sliding of the CdTe substrate wafer so that contact is no longer made with the solution; and (g) maintaining the temperature of said heated mercury between about 1° C. of a desired temperature and maintaining the temperature of the solution within about 1° C. of a desired temperature and wherein the heated mercury temperature is less than the temperature of the solution.

Claim 9

A process for preparing epitaxial layers of Hg 1-x Cd x Te on suitable substrates comprising the steps of: (a) placing an initial source material selected from the group consisting of tellurium, a mixture of mercury and tellurium or a mixture of mercury, tellurium and cadmium in a growth bin and a CdTe source wafer and substrate wafer in a slider insert; (b) heating the initial source material, source wafer and substrate wafer to a temperature at which simultaneously heated Hg in a boat produces a mercury vapor pressure over the source material and within time converts the initial source material to a solution material of mercury-tellurium or mercury-cadmium-tellurium; (c) sliding the CdTe source wafer so that contact is made with the solution for a period of time; (d) further sliding the CdTe source wafer so that contact is no longer made with the solution; (e) sliding the CdTe substrate wafer so that contact is made with the solution for a period of time sufficient to produce a desired thickness of epitaxial layer of HgCdTe on the CdTe substrate; (f) further sliding of the CdTe substrate wafer so that contact is no longer made with the solution; and (g) maintaining the temperature of said heated mercury between about 1° C. of a desired temperature and maintaining the temperature of the solution within about 1° C. of a desired temperature and wherein the heated mercury temperature is less than the temperature of the solution.

Claim 10

A process according to claim 6 wherein a plurality of layers of mercury cadmium telluride are grown onto the substrate thereby producing multi-layer structures.

Claim 11

A process according to claims 6 or 7 wherein the epitaxial layer is subsequently subjected to a heat treatment to adjust its native defect density, which in turn adjusts the free carrier concentration.

Claim 12

A process according to claims 6 or 7 wherein chemical impurities are added to the growth solution material or mercury vapor to effect doping the epitaxial layer to form an n-type or p-type layer.