Processing approach towards the formation of thin-film Cu(In,Ga)Se2

A method of fabricating a group IB-IIIA-VIA polycrystalline semiconductor material, comprising:

• a) determining a desired ratio of group IB metal atomic species to group IIIA metal atomic species for the polycrystalline semiconductor material;
• b) depositing a layered amorphous precursor onto an unheated or actively cooled substrate by sequentially depositing a plurality of individual amorphous precursor layers, the individual precursor layers formed by providing a flux of either i) one or more of the desired group IB metal atomic species, or ii) one or more of the desired group IIIA metal atomic species, but not both i) and ii);
• and with said flux of group IB or IIIA metal atomic species accompanied by a flux of group VIA nonmetal atomic species;
• wherein the layered amorphous precursor includes group IB metal atomic species and group IIIA metal atomic species along with about 40-70 atomic percent of the group VIA nonmetal atomic species, and, further, with group IB metal atomic species and group IIIA metal atomic species proportioned in relation to each other to provide said desired ratio of group IB metal atomic species to group IIIA metal atomic species;
• and
• c) annealing the layered amorphous precursor on the substrate at an elevated temperature above room temperature and then cooling to recrystallize the group IB, group IIIA, and group VIA atomic species to produce the polycrystailine semiconductor material.

A method of fabricating a polycrystalline CuInSe2 semiconductor material, comprising:

• determining a desired ratio of Cu to In for the polycrystalline CuInSe2 semiconductor material;
• depositing a layered amorphous precursor onto an unheated or actively cooled substrate by sequentially depositing by means of atomic flux a plurality of individual amorphous precursor layers with:
• (i) a flux for at least one of the individual precursor layers comprising Cu accompanied by a flux of Se and substantially no flux of In, to produce an amorphous Cu-Se layer, with the Se constituting 40-70 atomic percent of this individual precursor layer,
• (ii) a flux for at least another of the individual precursor layers comprising In accompanied by a flux of Se and substantially no flux of Cu, to produce an amorphous In-Se layer, with the Se constituting 40-70 atomic percent of this individual precursor layer, and
• (iii) further, depositing enough of the Cu and In in the respective individual precursor layers to make the layered amorphous precursor include the desired ratio of Cu to In;
• and
• annealing the layered amorphous precursor on the substrate at an elevated temperature above room temperature and then cooling to recrystallize the Cu, In, and Se to produce the polycrystalline CuInSe2 semiconductor material.