Thin-film devices formed from solid particles
Methods and devices are provided for forming thin-films from solid group IIIA-based particles. In one embodiment of the present invention, a method is described comprising of providing a first material comprising an alloy of a) a group IIIA-based material and b) at least one other material. The material may be included in an amount sufficient so that no liquid phase of the alloy is present within the first material in a temperature range between room temperature and a deposition or pre-deposition temperature higher than room temperature, wherein the group IIIA-based material is otherwise liquid in that temperature range. The other material may be a group IA material. A precursor material may be formulated comprising a) particles of the first material and b) particles containing at least one element from the group consisting of: group IB, IIIA, VIA element, alloys containing any of the foregoing elements, or combinations thereof.
1. A method comprising:
providing a first material comprising an alloy of a) a group IIIA-based material and b) at least one group IA-based material, wherein the group IA-based material is included in an amount sufficient so that no liquid phase of the alloy is present within the first material in a temperature range between room temperature and a deposition or pre-deposition temperature higher than room temperature, wherein the group IIIA-based material is otherwise liquid in that temperature range; and
formulating a precursor material comprising a) particles of the first material and b) particles containing at least one element from the group consisting of: group IB, IIIA, VIA element, alloys containing any of the foregoing elements, or combinations thereof.
2. The method of claim 1 further comprising:
formulating an ink including the precursor material;
solution depositing the ink onto a substrate to form a precursor layer on the substrate; and
reacting the precursor layer in a suitable atmosphere to form a group IB-IIIA-VIA based film.
3. The method of claim 2 wherein the alloy containing particles are a sole source of group IIIA elements in the ink.
4. The method of claim 2 wherein the film has a Cu/(In+Ga) compositional range of about 0.01 to about 1.0 and a Ga/(In+Ga) compositional range of about 0.01 to about 1.0.
5. The method of claim 2 wherein the film has a Cu/(In+Ga) compositional range of about >1.0 for Cu/(In+Ga) and a Ga/(In+Ga) compositional range of about 0.01 to about 1.0.
6. The method of claim 2 wherein the film has a Cu/(In+Ga) compositional range of about 0.01 to about 1.0 and a Ga/(In+Ga) compositional range of about 0.01 to about 1.0.
7. The method of claim 2 wherein the film has a desired Cu/(In+Ga) molar ratio is in the range of about 0.7 to about 1.0 and a desired Ga/(Ga+n) molar ratio in the range of about 0.1 to about 0.8.
8. The method of claim 2 wherein the ink includes a carrier liquid.
9. The process of claim 1 wherein the material comprises Al to make solid Al—Ga particles.
10. The process of claim 1 wherein the material comprises Al; wherein Ga dissolves in Al to make solid Al—Ga particles for use in forming a film of CAGS and/or CAIGS.
11. The method of claim 1 wherein the precursor material comprises a precursor material that forms a Cu—In—Se based alloy when sintered at the first temperature profile.
12. The method of claim 1 wherein the precursor material comprises a precursor material that forms a Cu—In—Se based alloy when sintered at the first temperature profile and combines with the alloy to form a Cu—In—Ga—Se based alloy when further heated through the second temperature profile.
13. The method of claim 1 wherein the precursor material comprises a precursor material that forms a Cu—In—Ga—Se based alloy when sintered at the first temperature profile and combines with the alloy to form a Cu—In—Ga—Se based alloy with further heating through the second temperature profile, resulting in increased Ga content near a top surface of the layer.
14. The method of claim 1 wherein:
the film has a desired Cu/(In+Ga) molar ratio in the range of greater than about 1.0 and a desired Ga/(Ga+n) molar ratio in the range of about 0.1 to about 0.8;
further reacting the film in a post-reacting step to change Cu/(In+Ga) to be in a range less than about 1.0.
15. The method of claim 1 wherein the precursor material is deposited on a substrate comprising a metal foil with a bottom layer selected from the group consisting of: Mo, Cu, Ag, Al, Ta, Ni, Cr, NiCr, or steel.