Method and apparatus providing single step vapor chloride treatment and photovoltaic modules

Abstract

A method and apparatus are disclosed in which cadmium chloride is deposited on a cadmium telluride layer while simultaneously heat treating the cadmium telluride layer.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . A method of manufacturing a photovoltaic module, the method comprising:
 forming a cadmium telluride layer on a substrate;   moving the substrate and cadmium telluride layer through a controlled ambient deposition oven, the oven having associated structures to control internal oxygen levels during a deposition;   forming a cadmium chloride vapor from powdered cadmium chloride in a vaporization unit; wherein the powdered cadmium chloride is continuously supplied to the vaporization unit;   depositing the cadmium chloride vapor from the vaporization unit on the cadmium telluride layer in the oven as the substrate and cadmium telluride layer move therethrough; and   heat treating the cadmium telluride layer in the oven to increase grain size,   wherein depositing the cadmium chloride vapor occurs at the same time as heat treating the cadmium telluride layer to provide a single continuous process step of cadmium chloride deposition and heat treatment of the cadmium telluride layer within the oven.   
     
     
         2 . The method of  claim 1 , wherein the substrate is transported through the oven on a belt or a plurality of rollers. 
     
     
         3 . The method of  claim 1 , wherein the cadmium telluride layer is heat treated by at least one heater arranged in the oven. 
     
     
         4 . The method of  claim 1 , wherein the vaporization unit is arranged inside the oven. 
     
     
         5 . The method of  claim 4 , further comprising inputting the vaporized cadmium chloride into the oven through a diffuser. 
     
     
         6 . The method of  claim 1 , wherein the oven is maintained at a temperature of about 350 to about 600 degrees Celsius while heat treating the cadmium telluride layer. 
     
     
         7 . The method of  claim 1 , wherein the oven is maintained at a temperature of about 400 to about 450 degrees Celsius while heat treating the cadmium telluride layer. 
     
     
         8 . The method of  claim 1 , wherein the vaporizer unit is arranged outside the oven. 
     
     
         9 . The method of  claim 8 , further comprising inputting the vaporized cadmium chloride into the oven through a diffuser. 
     
     
         10 . The method of  claim 1 , further comprising supplying a carrier gas to the vaporizer unit to distribute the vaporized cadmium chloride. 
     
     
         11 . The method of  claim 10 , wherein the carrier gas comprises at least one of hydrogen, helium, nitrogen, neon, argon, krypton, and mixtures thereof. 
     
     
         12 . The method of  claim 1 , wherein a cadmium sulfide layer is arranged on the substrate, and wherein the cadmium telluride layer is formed on the cadmium sulfide layer. 
     
     
         13 . The method of  claim 12 , wherein the cadmium sulfide layer comprises cadmium zinc sulfide. 
     
     
         14 . The method of  claim 1 , wherein the associated structures comprise load/exit locks or gas curtains, the method further comprising activating the load/exit locks or gas curtains to control internal oxygen levels of the oven during deposition of the cadmium chloride vapor. 
     
     
         15 . An apparatus for manufacturing a photovoltaic module, comprising:
 a controlled ambient oven comprising a heater for heat treating a cadmium telluride layer arranged on a substrate;   a vaporization unit for vaporizing powdered cadmium chloride;   a conveyor for continuously moving the substrate and cadmium telluride layer through the oven;   a diffuser arranged inside the oven for continuously diffusing vaporized cadmium chloride from the vaporization unit within the oven and depositing cadmium chloride vapor onto the cadmium telluride layer as the substrate moves through the oven, wherein depositing the cadmium chloride occurs within the oven at the same time as heat treating the cadmium telluride layer to provide a continuous single step deposition of the cadmium chloride and heat treatment of the cadmium telluride layer within the oven.   
     
     
         16 . The apparatus of  claim 15 , further comprising a transport mechanism arranged inside the oven for transporting the substrate through the oven. 
     
     
         17 . The apparatus of  claim 16 , wherein the transport mechanism comprises a belt or a plurality of rollers. 
     
     
         18 . The apparatus of  claim 15 , wherein the vaporization unit is an in-situ vaporization unit arranged within the oven. 
     
     
         19 . The apparatus of  claim 15 , wherein the oven comprises load/exit locks or gas curtains to control internal oxygen levels of the oven.