Fabrication process for photovoltaic cell

Abstract

A photovoltaic strip is physically separated from a semiconductor wafer utilizing physical sawing or other techniques. In accordance with one embodiment, a type of semiconductor wafer is first determined by interrogating the wafer to identify one or more of its optical, thermal, or electrical characteristics. This information regarding substrate type is then communicated to a separation apparatus, which then accomplishes precise physical separation of the substrate into discrete strips. Electrical performance of the strips may be tested prior to their incorporation into an assembled solar cell, where they are coupled to a concentrating element utilizing an elastomer encapsulant.

1 . A method for creating a photovoltaic strip for incorporation into a solar cell, the method comprising:
 providing a semiconductor wafer having a PN junction and a first electrical contact and a second electrical contact, the semiconductor wafer further comprising a photovoltaic strip;   interrogating the semiconductor wafer to identify its type; and   physically separating the photovoltaic strip from the semiconductor wafer based upon the wafer type.   
     
     
         2 . The method of  claim 1  wherein the semiconductor wafer is interrogated utilizing at least one of optical, electrical, and thermal techniques. 
     
     
         3 . The method of  claim 1  further comprising incorporating the semiconductor strip into an assembled solar cell. 
     
     
         4 . The method of  claim 3  further comprising testing electrical characteristics of the photovoltaic strip prior to its incorporation into the solar cell. 
     
     
         5 . The method of  claim 4  wherein testing the photovoltaic strip comprises testing at least one of current/voltage curve (IV-curve), short-circuit current (Isc), open circuit voltage (Voc), efficiency, and fill factor. 
     
     
         6 . The method of  claim 1  wherein the photovoltaic strip is physically separated by sawing. 
     
     
         7 . The method of  claim 6  wherein the sawing creates a scribe line, and the photovoltaic stripe is physical separated by fracturing along an axis of a unit cell. 
     
     
         8 . The method of  claim 6  wherein the first and second electrical contacts are present on a back side of the semiconductor wafer, wherein a front side of the wafer is sawed. 
     
     
         9 - 13 . (canceled) 
     
     
         14 . An apparatus for testing a photovoltaic strip, the apparatus comprising:
 a jig comprising a surface;   a first electrical contact located on a first side of the jig surface, the first electrical contact in electrical communication with a first terminal of a power supply;   a second electrical contact located on a second side of the jig surface opposite to the first side, the second electrical contact in electrical communication a second terminal of the power supply; and   a member for securing a photovoltaic strip onto the surface, such that a region of a first conductivity type in the substrate is in electrical communication with the first electrical contact, and a region of the second conductivity type in the substrate is in electrical communication with the second electrical contact.   
     
     
         15 . The apparatus of  claim 14  wherein the first and second electrical contacts are configured to be in electrical communication with a variable power supply in order to evaluate at least one of current/voltage curve (IV-curve), short-circuit current (Isc), open circuit voltage (Voc), efficiency, and fill factor of a supported photovoltaic strip. 
     
     
         16 . An apparatus for identifying a type of semiconductor substrate, the apparatus comprising:
 a member configured to support a substrate thereon;   a first conducting pin configured to be in electrical communication with a first electrical contact located on a back side of the supported substrate; and   a second conducting pin configured to be in electrical communication with a second electrical contact located on front side of the supported substrate.   
     
     
         17 . The apparatus of  claim 16  further comprising a light source configured to illuminate a front surface of the substrate in order to provoke electrical output therefrom detected by at least one of the first and second pins. 
     
     
         18 . The apparatus of  claim 16  further comprising a detector configured to detect ohmic heating on the substrate resulting from application of a potential difference applied between the first and second pins. 
     
     
         19 . The apparatus of  claim 16  further comprising an optical scanner configured to detect a pattern of conducting lines on a surface of the substrate. 
     
     
         20 . The apparatus of  claim 16  further comprising a processor in electrical communication with a database storing information regarding characteristics of a plurality of semiconductor types.