Abstract: Methods and systems are disclosed for processing a precursor material. The method includes introducing a substrate having a precursor material deposited on a surface of the substrate into a first zone of a vacuum chamber. The precursor material comprises copper, indium, and at least one of gallium, selenium, sulfur, sodium, antimony, boron, aluminum, and silver. The method further includes, within the first zone, heating the precursor material to a target reaction temperature within a range of about 270° C. to about 490° C. The method further includes maintaining a selenium vapor in a second zone of the vacuum chamber, and after heating the precursor material to the target reaction temperature, introducing the precursor material and the substrate to the second zone of the vacuum chamber.