Cadmium diffused Pb1-x Snx Te diode laser

Claim 1

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: placing a body of low dislocation density monocrystalline P-type semiconductive material in a chamber to receive cadmium as a diffusant, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 30 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 32 microns; placing in said chamber a quantity of cadmium that is equal to about 0.05 - 0.08 milligrams of cadmium per cubic centimeter of chamber volume; closing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said chamber at a preselected rate of about 50° - 500° C. per hour to a diffusion temperature of about 350° - 500° C.; maintaining said diffusion temperature for a preselected duration up to about 2 hours to diffuse cadmium into a surface of said body and form a planar, high injection efficiency PN junction in said body that is parallel to and at a preselected depth below said surface; cooling said body in said chamber from said diffusion temperature at a preselected rate of about 50° - 500° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said chamber at any time, after said body has been cooled to about 150° C. in said chamber; contouring and polishing said body into a predetermined form that has a laser cavity adjacent said PN junction for collecting and amplifying infrared radiation of said predetermined wavelength; applying ohmic contacts to said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and placing said contoured and polished body in intimate thermal association with cooling means for removing heat produced during generation, collection and amplification of said infrared radiation.

Claim 2

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: placing a body of low dislocation density monocrystalline P-type semiconductive material in a chamber to receive cadmium as a diffusant, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 30 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 32 microns; placing in said chamber a quantity of cadmium that is equal to about 0.05 - 0.08 milligrams of cadmium per cubic centimeter of chamber volume; closing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said chamber at a preselected rate of about 50° - 500° C. per hour to a diffusion temperature of about 350° - 500° C.; maintaining said diffusion temperature for a preselected duration up to about 2 hours to diffuse cadmium into a surface of said body and form a planar, high injection efficiency PN junction in said body that is parallel to and at a preselected depth below said surface; cooling said body in said chamber from said diffusion temperature at a preselected rate of about 50° - 500° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said chamber at any time, after said body has been cooled to about 150° C. in said chamber; contouring and polishing said body into a predetermined form that has a laser cavity adjacent said PN junction for collecting and amplifying infrared radiation of said predetermined wavelength; applying ohmic contacts to said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and placing said contoured and polished body in intimate thermal association with cooling means for removing heat produced during generation, collection and amplification of said infrared radiation.

Claim 3

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: placing a body of low dislocation density monocrystalline P-type semiconductive material in a chamber to receive cadmium as an N-type conductivity determining diffusion, said monocrystalline body having a (100) crystal plane and a surface parallel thereto, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 30 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 32 microns; placing in said chamber a quantity of cadmium that is equal to about 0.05 - 0.08 milligrams of cadmium per cubic centimeter of chamber volume; closing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said closed chamber at a preselected rate of about 100° - 200° C. per hour to a diffusion temperature of about 400° - 500° C.; maintaining said diffusion temperature for a preselected duration of the order of about 1 hour to diffuse cadmium into said body surface and form a planar, high injection efficiency PN junction in said body that is parallel to and at a preselected depth below said surface; cooling said body in said closed chamber from said diffusion temperature at a preselected rate of about 100° - 200° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said closed chamber at any time, after said body has been cooled to about 150° C. in said chamber; contouring and polishing said body into a parallelepiped that has a laser cavity adjacent said PN junction for collecting and amplifying infrared radiation of said predetermined wavelength; applying ohmic contacts to said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and placing said parallelepiped in intimate thermal communication with cooling means for removing heat produced during generation, collection and amplification of said infrared radiation.

Claim 4

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: placing a body of low dislocation density monocrystalline P-type semiconductive material in a chamber to receive cadmium as an N-type conductivity determining diffusion, said monocrystalline body having a (100) crystal plane and a surface parallel thereto, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 30 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 32 microns; placing in said chamber a quantity of cadmium that is equal to about 0.05 - 0.08 milligrams of cadmium per cubic centimeter of chamber volume; closing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said closed chamber at a preselected rate of about 100° - 200° C. per hour to a diffusion temperature of about 400° - 500° C.; maintaining said diffusion temperature for a preselected duration of the order of about 1 hour to diffuse cadmium into said body surface and form a planar, high injection efficiency PN junction in said body that is parallel to and at a preselected depth below said surface; cooling said body in said closed chamber from said diffusion temperature at a preselected rate of about 100° - 200° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said closed chamber at any time, after said body has been cooled to about 150° C. in said chamber; contouring and polishing said body into a parallelepiped that has a laser cavity adjacent said PN junction for collecting and amplifying infrared radiation of said predetermined wavelength; applying ohmic contacts to said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and placing said parallelepiped in intimate thermal communication with cooling means for removing heat produced during generation, collection and amplification of said infrared radiation.

Claim 5

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: polishing opposite surfaces of an elongated low dislocation density monocrystalline P-type semiconductive material parallel to its (100) crystal plane to form flat and parallel opposite surfaces on said body spaced about 400 - 600 micrometers apart, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 8 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 9 microns and having a tellurium content up to 0.01 mol percent in excess of 50 mol percent to induce said P-type conductivity; placing said body in a chamber for receiving cadmium as and N-type conductivity determining diffusant; placing in said chamber a quantity of cadmium that is equal to about 0.06 - 0.07 milligrams of cadmium per cubic centimeter of chamber volume; sealing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said sealed chamber at a preselected rate of the order of about 100° C. per hour to a diffusion temperature of about 400° - 500° C.; maintaining said diffusion temperature for a preselected duration up to about 1/2 - 11/2 hours to diffuse cadmium into both of said opposite surfaces of said body and form a planar, high injection efficiency PN junction in said body that is parallel to said surfaces and at a preselected depth, within a range of 20 - 100 micrometers, below said surfaces; cooling said body in said sealed chamber from said diffusion temperature at a preselected rate of the order of 100° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said chamber at any time, after said body has been cooled to about 150° C. in said chamber; polishing one of said opposite surfaces of said body to remove its cadmium diffusion layer and reduce body thickness to less than about 250 micrometers; cleaving said body along said (100) crystal planes perpendicular to said opposite surfaces to form an elongated parallelepiped less than about 200 micrometers wide and about 300 - 600 micrometers long; polishing end surfaces of said elongated parallelepiped body to a reflective surface finish to form a laser cavity about 250 - 500 micrometers long adjacent said PN junction for collecting and amplifying said infrared radiation of predetermined wavelength; forming a discrete ohmic contact to each of said opposite surfaces of said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and soldering the parallelepiped body surface containing the remaining cadmium diffusion layer to a cooling member for removing heat produced in said body adjacent said PN junction during generation, collection and amplification of said infrared radiation.

Claim 6

A method of making a higher power, more tunable lead-tin telluride infrared laser, said method comprising: polishing opposite surfaces of an elongated low dislocation density monocrystalline P-type semiconductive material parallel to its (100) crystal plane to form flat and parallel opposite surfaces on said body spaced about 400 - 600 micrometers apart, said semiconductive material having the composition Pb 1-x Sn x Te with x being a value from zero to about 8 mol percent that is selected to provide a band gap corresponding to a photon of infrared radiation of a predetermined wavelength within a range of 6.5 - 9 microns and having a tellurium content up to 0.01 mol percent in excess of 50 mol percent to induce said P-type conductivity; placing said body in a chamber for receiving cadmium as and N-type conductivity determining diffusant; placing in said chamber a quantity of cadmium that is equal to about 0.06 - 0.07 milligrams of cadmium per cubic centimeter of chamber volume; sealing said chamber while it is evacuated to a pressure no greater than about 1 × 10 -6 Torr; heating said sealed chamber at a preselected rate of the order of about 100° C. per hour to a diffusion temperature of about 400° - 500° C.; maintaining said diffusion temperature for a preselected duration up to about 1/2 - 11/2 hours to diffuse cadmium into both of said opposite surfaces of said body and form a planar, high injection efficiency PN junction in said body that is parallel to said surfaces and at a preselected depth, within a range of 20 - 100 micrometers, below said surfaces; cooling said body in said sealed chamber from said diffusion temperature at a preselected rate of the order of 100° C. per hour to a temperature of about 150° C.; cooling said body to room temperature at any rate, and removing it from said chamber at any time, after said body has been cooled to about 150° C. in said chamber; polishing one of said opposite surfaces of said body to remove its cadmium diffusion layer and reduce body thickness to less than about 250 micrometers; cleaving said body along said (100) crystal planes perpendicular to said opposite surfaces to form an elongated parallelepiped less than about 200 micrometers wide and about 300 - 600 micrometers long; polishing end surfaces of said elongated parallelepiped body to a reflective surface finish to form a laser cavity about 250 - 500 micrometers long adjacent said PN junction for collecting and amplifying said infrared radiation of predetermined wavelength; forming a discrete ohmic contact to each of said opposite surfaces of said body by which a voltage can be applied across said PN junction to generate said infrared radiation of predetermined wavelength for collection and amplification in said laser cavity; and soldering the parallelepiped body surface containing the remaining cadmium diffusion layer to a cooling member for removing heat produced in said body adjacent said PN junction during generation, collection and amplification of said infrared radiation.