Patent ID: 7858151

Claim:
A method for forming an absorber layer containing elements of groups IB, IIIA and VIA, comprising the steps of: atomic monolayer resolution tuning of a bandgap grading of a precursor layer on a substrate, wherein the tuning occurs with spatial uniformity and resolution through deposition of at least two types of partial atomic monolayers, one of the types comprises of a different group IB, IIIA, or VIA material relative to a group IB, IIIA, or VIA material in another of the types, with aggregate growth rate directly proportional to a number of reaction cycles rather than the pressure or concentration of precursor gases in the chamber, with control over film thickness, film uniformity, and conformality; processing the substrate in a roll-to-roll process by using an elongate treatment chamber; wherein processing includes annealing the substrate with a precursor layer-thereon in one or more steps; wherein the deposition of partial atomic monolayers comprises: exposing a target surface of the substrate to a group IB, IIIA, or VIA precursor agent and then a reducing agent, wherein deposited atoms occupy only a portion of all deposition sites on the target surface; repeating the deposition of partial atomic monolayers using same or different group IB, IIIA, or VIA precursor agents and reducing agents until a desired atomically-graded deposition profile of at least two materials from the group consisting of group IB, IIIA, and VIA is formed in the precursor layer.