Method and apparatus for forming a transparent conductive oxide using hydrogen

Abstract

A method and apparatus for forming a crystalline cadmium stannate layer of a photovoltaic device by heating an amorphous layer in the presence of hydrogen gas.

1 - 18 . (canceled) 
     
     
         19 . An apparatus for forming a crystalized cadmium stannate layer of a photovoltaic device, comprising:
 a multiple-zone oven comprising separate transformation and semiconductor zones;   at least one heater for heating the transformation zone;   a transport mechanism for transporting a substrate containing an amorphous layer containing cadmium and tin through the multi-zone oven;   a first gas source for supplying hydrogen gas into the transformation zone for contact with the transported substrate.   
     
     
         20 . The apparatus of  claim 19 , wherein the semiconductor zone is configured for a semiconductor deposition technique selected from the group consisting of vapor transport deposition, close space sublimation, evaporation and sputtering. 
     
     
         21 . The apparatus of  claim 20 , wherein the semiconductor zone is configured for vapor transport deposition. 
     
     
         22 . The apparatus of  claim 19 , further comprising a diffuser arranged inside the transformation zone for diffusing the hydrogen gas. 
     
     
         23 . The apparatus of  claim 19 , wherein the first gas source is configured to supply a gas mixture comprising hydrogen gas and an inert gas into the tranformation zone for contact with the transported substrate. 
     
     
         24 . The apparatus of  claim 23 , wherein the inert gas comprises one of argon, nitrogen and helium. 
     
     
         25 . The apparatus of  claim 24 , wherein the inert gas comprises helium. 
     
     
         26 . The apparatus of  claim 19 , further comprising a second gas source for supplying an inert gas into the transformation zone. 
     
     
         27 . The apparatus of  claim 26 , wherein the inert gas comprises one of argon, nitrogen and helium. 
     
     
         28 . The apparatus of  claim 27 , wherein the inert gas comprises helium. 
     
     
         29 . The apparatus of  claim 19 , wherein the at least one heater is configured to heat the transformation zone to a temperature of about 500° C. to about 650° C. 
     
     
         30 . The apparatus of  claim 19 , wherein the hydrogen gas converts the amorphous layer into a crystalized cadmium stannate layer. 
     
     
         31 . The apparatus of  claim 30  further comprising a sputtering apparatus in the transformation zone for depositing a buffer layer over the crystalized cadmium stannate layer. 
     
     
         32 . The apparatus of  claim 19 , wherein the transformation zone contains hydrogen gas at a concentration of about 0.01% to about 10%. 
     
     
         33 . The apparatus of  claim 31 , wherein the hydrogen gas concentration is about 1%.