Apparatus and methods for manufacturing thin-film solar cells

Abstract

Improved methods and apparatus for forming thin-film layers of semiconductor material absorber layers on a substrate web. According to the present teachings, a semiconductor layer may be formed in a multi-zone process whereby various layers are deposited sequentially onto a moving substrate web.

What is claimed is: 
     
         1 . A method of depositing a semiconductor absorber layer onto a flexible substrate web, comprising:
 transporting a continuous flexible substrate web from a pay-out roll through a plurality of deposition zones and then to a take-up roll while maintaining a tension on the substrate sufficient for the substrate to maintain a substantially flat surface in each of the deposition zones, wherein transporting the substrate web through the deposition zones includes:
 partially wrapping the substrate web around a first transport roller by a first wrap angle, to orient the substrate web at a first angle relative to the horizontal; 
 passing the substrate web through a first substantially enclosed gallium indium deposition zone at the first angle; 
 partially wrapping the substrate web around a second transport roller by a second wrap angle, to orient the substrate web at a second angle relative to the horizontal; 
 passing the substrate through a first substantially enclosed copper deposition zone at the second angle; 
 partially wrapping the substrate web around a third transport roller by a third wrap angle, to orient the substrate web at a third angle relative to the horizontal; and 
 passing the substrate through a second substantially enclosed gallium indium deposition zone at the third angle; 
   receiving the substrate with a take-up roll; and   wherein within each deposition zone, a substantially enclosed effusion assembly deposits material onto the substrate as the substrate passes through the deposition zone.   
     
     
         2 . The method of  claim 1 , wherein the wrap angles are each sufficient to create enough friction to cause the roller to rotate with the moving substrate web and thereby to prevent the substrate web from sliding across the roller. 
     
     
         3 . The method of  claim 2 , wherein the wrap angles are each in the range of 3-10 degrees. 
     
     
         4 . The method of  claim 3 , wherein the wrap angles are each approximately 7 degrees. 
     
     
         5 . The method of  claim 1 , wherein the tension on the substrate web is at least 30 pounds. 
     
     
         6 . The method of  claim 1 , wherein the substrate web is 30 centimeters wide, and the tension on the substrate web is in the range of 30-35 pounds. 
     
     
         7 . The method of  claim 1 , wherein the pay-out roll and the take-up roll are driven by independent motors. 
     
     
         8 . A method of depositing a semiconductor absorber layer onto a flexible substrate web, comprising:
 maintaining a tension of approximately 30-35 pounds on a substrate web; and   while maintaining the tension of approximately 30-35 pounds:
 partially wrapping the substrate web around a first transport roller by a first wrap angle, to orient the substrate web at a first angle relative to the horizontal; 
 passing the substrate web through a first substantially enclosed gallium indium deposition zone at the first angle; 
 partially wrapping the substrate web around a second transport roller by a second wrap angle, to orient the substrate web at a second angle relative to the horizontal; 
 passing the substrate through a first substantially enclosed copper deposition zone at the second angle; 
 partially wrapping the substrate web around a third transport roller by a third wrap angle, to orient the substrate web at a third angle relative to the horizontal; and 
 passing the substrate through a second substantially enclosed gallium indium deposition zone at the third angle; 
   wherein within each deposition zone, a substantially enclosed effusion assembly deposits material onto the substrate as the substrate passes through the deposition zone.   
     
     
         9 . The method of  claim 8 , wherein the wrap angles are each sufficient to create enough friction to cause the roller to rotate with the moving substrate web and thereby to prevent the substrate web from sliding across the roller. 
     
     
         10 . The method of  claim 9 , wherein the wrap angles are each in the range of 3-10 degrees. 
     
     
         11 . The method of  claim 10 , wherein the wrap angles are each approximately 7 degrees. 
     
     
         12 . The method of  claim 8 , wherein the substrate web is 30 centimeters wide. 
     
     
         13 . The method of  claim 8 , wherein the pay-out roll and the take-up roll are driven by independent motors. 
     
     
         14 . A method of depositing a semiconductor absorber layer onto a flexible substrate web, comprising:
 providing a substrate web under tension sufficient to maintain a substantially flat surface of the web in each of a plurality of deposition zones;   orienting the substrate web at a first angle relative to the horizontal by partially wrapping the substrate web around a first free roller by a first wrap angle sufficient to prevent the substrate web from sliding across the first roller;   passing the substrate web through a first substantially enclosed gallium indium deposition zone at the first angle;   orienting the substrate web at a second angle relative to the horizontal by partially wrapping the substrate web around a second free roller by a second wrap angle sufficient to prevent the substrate web from sliding across the second roller;   passing the substrate through a first substantially enclosed copper deposition zone at the second angle;   orienting the substrate web at a third angle relative to the horizontal by partially wrapping the substrate web around a third free roller by a third wrap angle sufficient to prevent the substrate web from sliding across the third roller; and   passing the substrate through a second substantially enclosed gallium indium deposition zone at the third angle;   wherein within each deposition zone, a substantially enclosed effusion assembly deposits material onto the substantially flat surface of the web as the web passes through the deposition zone.   
     
     
         15 . The method of  claim 14 , wherein the tension is at least 30 pounds. 
     
     
         16 . The method of  claim 15 , wherein the substrate web is 30 centimeters wide. 
     
     
         17 . The method of  claim 14 , wherein the wrap angles are each in the range of 3-10 degrees. 
     
     
         18 . The method of  claim 17 , wherein the wrap angles are each approximately 7 degrees. 
     
     
         19 . The method of  claim 14 , wherein tension is maintained on the web by independent motors of a pay-out roll and a take-up roll. 
     
     
         20 . The method of  claim 14 , wherein each substantially enclosed effusion assembly includes an aperture formed in a top surface angled to compliment the angle of the substrate in the associated deposition zone.