Formation of Photoconductive and Photovoltaic Films

Abstract

The present application discloses a method and system of depositing a lead selenide film onto another material. The lead selenide film may used in a photoconductive application or a photovoltaic application. Furthermore, the applications may be responsive to infrared radiation at ambient temperature. In one embodiment, a method includes sputtering the lead selenide film, performing a sensitization process, and applying a passivation film. In one exemplary embodiment, a p-n junction is formed by directly adhering a lead selenide film to a silicon substrate.

1 . A substrate comprising:
 a lead selenide film directly adhered to the substrate, wherein the material of the substrate has a coefficient of thermal expansion different than lead selenide material;   wherein the substrate is configured to respond to infrared radiation at ambient temperature.   
     
     
         2 . The substrate of  claim 1 , wherein the substrate is a silicon substrate, 
     
     
         3 . The substrate of  claim 1 , absent a glass layer between the lead selenide film and the substrate. 
     
     
         4 . The substrate of  claim 3 , wherein the lead selenide film is configured for at least one of photoconductive and photovoltaic applications. 
     
     
         5 . The substrate of  claim 1 , further comprising a passivation film on the lead selenide film, wherein the passivation film is configured to substantially eliminate alteration of electrical properties of the substrate in response to exposure to contaminants. 
     
     
         6 . The substrate of  claim 1 , wherein the substrate is a silicon substrate or a gallium arsenide substrate. 
     
     
         7 . The substrate of  claim 1 , wherein the substrate is configured to respond to infrared radiation at ambient temperature by sensitizing the substrate, and wherein the sensitizing the substrate comprises:
 removing contaminants from a process chamber;   the process chamber with an inert gas; and   adding a combination of halogen, gas, nitrogen gas, and oxygen gas to the process chamber, wherein the process chamber is heated to about 300° C.   
     
     
         8 . The substrate of  claim 1 , wherein the halogen gas is at least one of fluorine, chlorine, bromine, iodine, and astatine. 
     
     
         9 . The substrate of  claim 1 , wherein the inert gas is nitrogen gas, and wherein the pressure of the process chamber is in the range of atmospheric pressure to 3 pounds per square inch. 
     
     
         10 . The substrate of  claim 1 , wherein the lead selenide film is configured for a photoconductive response greater than 10%. 
     
     
         11 . A method for creating a p-n junction on a substrate, said method comprising:
 sputtering a lead selenide film on the substrate, wherein the material of the substrate has a coefficient of thermal expansion different than lead selenide material;   heating the substrate in the range of 300°-400° C.; and   configuring a photovoltaic response of the lead selenide film to infrared radiation at ambient temperature.   
     
     
         12 . The method of  claim 11 , wherein the substrate is a silicon substrate. 
     
     
         13 . The method of  claim 11 , wherein the substrate is a gallium arsenide substrate. 
     
     
         14 . The method of  claim 11 , wherein the configuring the photovoltaic response comprises adding dopant materials to a sputtering target used in the sputtering the lead selenide film. 
     
     
         15 . The method of  claim 11 , wherein the configuring the photovoltaic response comprises adding a gas to a sputtering target used in the sputtering the lead selenide film. 
     
     
         16 . The method of  claim 11 , wherein the configuring the photovoltaic response comprises sensitizing the substrate, and wherein the sensitizing the substrate comprises:
 removing contaminants from a process chamber;   filling the process chamber with an inert gas; and   adding a combination of halogen gas, nitrogen gas, and oxygen gas to the process chamber, wherein the process chamber is heated to about 300° C.   
     
     
         17 . The method of  claim 16 , wherein the inert gas is nitrogen gas, and wherein the pressure of the process chamber is in the range of atmospheric pressure to 3 pounds per square inch. 
     
     
         18 . The method of  claim 16 , further comprising:
 adjusting a gas ratio of the combination of halogen gas, nitrogen gas, and oxygen gas; and   configuring electrical properties of the substrate via adjusting a time of exposure of the substrate to the combination of halogen gas, nitrogen gas, and oxygen gas.   
     
     
         19 . The method of  claim 16 , wherein the halogen gas is at least one of fluorine, chlorine, bromine, iodine, and astatine. 
     
     
         20 . The method of  claim 11 , wherein the lead selenide film is configured for a photoconductive response greater than 7%.