Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom
View Patent ↗Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.
1. A liquid-based preliminary precursor composition comprising:
a solvent comprising a primary amine; and
a solute comprising copper and selenium wherein the preliminary precursor composition is substantially free of oxygen-containing compounds.
2. The preliminary precursor composition of claim 1 , wherein the primary amine is selected from the group consisting of hydrazine and liquid alkylamines.
3. The preliminary precursor composition of claim 1 , wherein the primary amine is hydrazine.
4. The preliminary precursor composition of claim 1 , wherein the primary amine is present in greater than a stoichiometric amount.
5. The preliminary precursor composition of claim 1 further comprising a cosolvent.
6. The preliminary precursor composition of claim 5 , wherein the cosolvent is selected from the group consisting of secondary amines, lower, alkanols, and glycols.
7. The preliminary precursor composition of claim 6 , wherein the cosolvent is ethylene diamine.
8. A precursor composition comprising:
a liquid-based solvent comprising a primary amine; and
a solute comprising copper and selenium, the precursor composition being substantially free of oxygen containing compounds and at least substantially devoid of a precipitate comprising Cu 2 Se.
9. The precursor composition of claim 8 , wherein the primary amine is selected from the group consisting of hydrazine and alkylamines.
10. The precursor composition of claim 9 , wherein the primary amine is hydrazine.
11. The precursor composition of claim 8 , wherein after heating has a molecular signature characterized by Raman spectrum substantially as shown in FIG. 4 .
12. The precursor composition of claim 8 further comprising a cosolvent.
13. The precursor composition of claim 12 , wherein the amount of the cosolvent is up to the amount of the primary amine.
14. The precursor composition of claim 8 , wherein the amount of the primary amine is greater than a stoichiometric amount.
15. A thin film comprising the precursor composition of claim 8 heated to a temperature sufficient to remove the solvent.
16. The thin film of claim 15 heated to a temperature of from about 150° C. to 250° C.
17. The thin film of claim 16 heated to a temperature of from about 180° C. to 250° C.
18. The thin film of claim 15 comprising copper selenide at least substantially in the form of CuSe.
19. The thin film of claim 18 entirely in the form of CuSe.
20. The thin film of claim 15 containing substantially no oxygen or oxygen containing compounds.
21. The thin film of claim 15 , which is substantially amorphous.
22. The thin film of claim 15 , which is substantially crystalline.
23. The thin film of claim 15 , characterized by any one of the X-ray diffraction patterns as shown in FIG. 3 .
24. A method of making the liquid-based preliminary precursor composition of claim 1 comprising:
combining the solvent and the solute to form a solution; and
agitating the solution until a non-soluble product is formed.
25. A method of making the liquid-based precursor composition of claim 8 comprising:
combining the solvent and the solute to form a preliminary precursor composition;
agitating the preliminary precursor composition to form a non-soluble product; and
removing the non-soluble product to form the liquid-based precursor composition.
26. The method of claim 25 wherein the solvent is selected from the group consisting of hydrazine and alkylamines.
27. The method of claim 25 further comprising combining the solvent and a cosolvent with the solute.
28. A method of making a thin film comprising:
depositing the precursor composition of claim 8 on a substrate, and
heating the precursor composition for a time sufficient to remove the solvent.
29. The method of claim 28 further comprising heating the precursor composition to a temperature favoring the formation of CuSe.
30. The method of claim 29 further comprising conducting the heating step for a time sufficient to favor the formation of CuSe.