Atomic layer deposition of metal sulfide thin films using non-halogenated precursors
A method for preparing a metal sulfide thin film using ALD and structures incorporating the metal sulfide thin film. The method includes providing an ALD reactor, a substrate, a first precursor comprising a metal and a second precursor comprising a sulfur compound. The first and the second precursors are reacted in the ALD precursor to form a metal sulfide thin film on the substrate. In a particular embodiment, the metal compound comprises Bis(N,N′-di-sec-butylacetamidinato)dicopper(I) and the sulfur compound comprises hydrogen sulfide (H 2 S) to prepare a Cu 2 S film. The resulting metal sulfide thin film may be used in among other devices, photovoltaic devices, including interdigitated photovoltaic devices that may use relatively abundant materials for electrical energy production.
1. A method for preparing a portion of an interdigitated photovoltaic device, comprising:
providing an atomic layer deposition (ALD) reactor;
providing a high-aspect ratio substrate;
providing a first non-halogenated precursor comprising Bis(N,N′-di-sec-butylacetamidinato)dicopper(I);
providing a second non-halogenated precursor comprising a sulfur compound;
reacting the first non-halogenated precursor in the ALD reactor for a first period;
reacting the second non-halogenated precursor in the ALD reactor for a second period;
repeating the reactions of the first non-halogenated precursor and the second non-halogenated precursor for a number of cycles until a chalcocite film of a desired thickness is formed on the high-aspect ratio substrate.
2. The method of claim 1 , wherein the second non-halogenated precursor comprises H 2 S.
3. The method of claim 2 , wherein the chalcocite film consists essentially of Cu 2 S.
4. The method of claim 1 , wherein the chalcocite film consists essentially of a copper sulfide.
5. The method of claim 4 , wherein the copper sulfide is selected from the group of Cu x S, where x is about 1.8-2.2.
6. The method of claim 1 , wherein the chalcocite film is deposited on a transparent oxide conductor (TCO) electrode coupled to the high-aspect ratio substrate, and wherein the chalcocite film is further coupled to a n-type semiconductor.
7. The method of claim 6 , further comprising preparing an interdigitated photovoltaic device using the high-aspect ratio substrate.
8. The method of claim 1 , further comprising:
providing a purge gas; and
substantially purging the ALD reactor with the purge gas after at least one of the first period and the second period.
9. A method for preparing a Cu 2 S film on a substrate, comprising:
providing an atomic layer deposition (ALD) reactor;
providing a substrate;
providing a first non-halogenated precursor, the first precursor comprising Bis(N,N′-di-sec-butylacetamidinato)dicopper(I);
providing a second non-halogenated precursor, the second precursor comprising H 2 S;
heating the substrate to a reaction temperature;
exposing the substrate in the ALD reactor to the first non-halogenated precursor for a first predetermined duration;
exposing the substrate in the ALD reactor to the second non-halogenated precursor for a second predetermined duration;
repeating for a predetermined number of cycles exposure of the substrate in the ALD reactor to the first non-halogenated precursor and the second non-halogenated precursor to form a Cu 2 S film on the substrate.
10. The method of claim 9 , further comprising:
providing a purge gas; and
substantially purging the ALD reactor with the purge gas after at least one of the first predetermined duration and the second predetermined duration.
11. The method of claim 9 , wherein the substrate comprises a high-aspect ratio substrate.
12. A method for preparing a portion of an interdigitated photovoltaic device, comprising:
providing an atomic layer deposition (ALD) reactor;
providing a high-aspect ratio substrate;
providing a first non-halogenated precursor comprising Bis(N,N′-di-sec-butylacetamidinato)dicopper(I);
providing a second non-halogenated precursor comprising a sulfur compound;
reacting the first non-halogenated precursor in the ALD reactor for a first period;
reacting the second non-halogenated precursor in the ALD reactor for a second period; and
repeating the reactions of the first non-halogenated precursor and the second non-halogenated precursor for a number of cycles until a chalcocite film of a desired thickness is formed on the high-aspect ratio substrate;
wherein an average growth rate of the chalcocite film of at least about 0.9 Å per cycle is achieved.
13. The method of claim 12 , wherein the second non-halogenated precursor comprises H 2 S.
14. The method of claim 12 , wherein the chalcocite film consists essentially of a copper sulfide.
15. The method of claim 14 , wherein the copper sulfide is selected from the group of Cu x S, where x is about 1.8-2.2.
16. The method of claim 12 , wherein the chalcocite film is deposited on a transparent oxide conductor (TCO) electrode coupled to the high-aspect ratio substrate, and wherein the chalcocite film is further coupled to a n-type semiconductor.
17. The method of claim 16 , further comprising preparing an interdigitated photovoltaic device using the high-aspect ratio substrate.