Patent ID: 8404512

Claim:
A method of forming a doped Group IBIIIAVIA absorber layer on a base, the method comprising: depositing a precursor layer on the base, the precursor layer comprising a Group IB material film including Cu, a Group IIIA material film including at least one of In and Ga, a Group VIA material film including Se and a dopant material film that includes at least one of Na, K and Li; partially reacting the precursor layer at a first temperature range to form a doped semi absorber layer, wherein the step of partially reacting the precursor layer causes at least some of the dopant material to diffuse to at least a top surface of the doped semi absorber layer and form a dopant material rich film theron; applying a surface treatment to remove at least some of the dopant material rich film from the top surface of the doped semi-absorber layer, the surface treatment including applying a liquid including water to the top surface to remove the dopant material rich film, wherein the liquid has a pH of 1 to 4; and reacting the doped semi-absorber layer, after removing the at least some of the dopant material rich film, at a second temperature range to form a doped Group IBIIIAVIA absorber layer.