Patent ID: 8197703

Claim:
A method of forming solar cell absorbers on a surface of a base, comprising: forming a precursor layer on the surface of the base, the precursor layer comprising at least one Group IB material, a first Group IIIA material and a second Group IIIA material; reacting the precursor layer with a Group VIA material to form a Group IBIIIAVIA absorber layer with a first thickness having a front surface and a back surface adjacent the surface of the base, wherein the step of reacting non-uniformly distributes the second Group IIIA material within the Group IBIIIAVIA absorber layer so that a molar ratio of the second Group IIIA material to a total of the first Group IIIA material and the second Group IIIA material is less than 0.1 at the front surface and greater than 0.5 at the back surface; and applying a material removal process to the front surface of the Group IBIIIAVIA absorber layer, thus forming a modified front surface while reducing the thickness of the absorber layer to a second thickness, wherein the molar ratio of the second Group IIIA material to the total of the first Group IIIA material and the second Group IIIA material is in the range of 0.15-0.3 at the modified front surface.