Atomic layer deposition of quaternary chalcogenides
Methods and systems are provided for synthesis and deposition of chalcogenides (including Cu 2 ZnSnS 4 ). Binary compounds, such as metal sulfides, can be deposited by alternating exposures of the substrate to a metal cation precursor and a chalcogen anion precursor with purge steps between.
1. A method of synthesizing a Cu 2 ZnSnS 4 conformal layer, comprising the steps of:
depositing, via atomic layer deposition, a Cu 2 S layer;
depositing, via atomic layer deposition, a SnS 2 layer on the Cu 2 S layer; and
depositing, via atomic layer deposition, a ZnS layer on the SnS 2 layer;
forming Cu 2 ZnSnS 4 from the Cu 2 S layer, the ZnS layer, and the SnS 2 layer.
2. The method of claim 1 , further comprising annealing the Cu 2 S layer, SnS 2 layer, and ZnS layer to form Cu 2 ZnSnS 4 .
3. The method of claim 1 , wherein the depositing of the Cu 2 S layer, the SnS 2 layer, and the ZnS layer comprise the creation of a stack and further comprising the creation of a plurality of stacks.
4. The method of claim 1 , wherein an atomic layer deposition cycle for depositing Cu 2 S via atomic layer deposition comprises the steps of:
exposing the substrate to a fluid containing a gaseous copper-containing precursor;
purging the gaseous copper-containing precursor;
exposing the substrate to a fluid containing a gaseous sulfur-containing precursor; and
purging the gaseous sulfur-containing precursor.
5. The method of claim 1 , wherein an ALD cycle for depositing SnS 2 via atomic layer deposition comprises the steps of:
exposing the substrate to a fluid containing a gaseous tin-containing precursor;
purging the gaseous tin-containing precursor;
exposing the substrate to a fluid containing a gaseous sulfur-containing precursor; and
purging the gaseous sulfur-containing precursor.
6. The method of claim 1 , wherein an atomic layer deposition cycle for depositing ZnS via atomic layer deposition comprises the steps of:
exposing the substrate to a fluid containing a gaseous zinc-containing precursor;
purging the gaseous zinc-containing precursor;
exposing the substrate to a fluid containing a gaseous sulfur-containing precursor; and
purging the gaseous zinc-containing precursor.
7. The method of claim 1 wherein the forming occurs via temporal atomic layer deposition.
8. The method of claim 1 wherein the forming occurs via spatial atomic layer deposition.
9. A method of synthesizing a Cu 2 ZnSnS 4 conformal layer, comprising the steps of:
creating N Cu 2 S/SnS 2 /ZnS stacks by:
depositing via X number of cycles of atomic layer deposition Cu 2 S;
depositing via Y number of cycles of atomic layer deposition SnS 2 ; and
depositing via Z number of cycles of atomic layer deposition ZnS.
10. The method of claim 9 , wherein X is greater than or equal to 1.
11. The method of claim 9 wherein Y is greater than or equal to 1.
12. The method of claim 9 wherein Z is greater than or equal to 1.
13. The method of claim 9 , wherein N is 1.
14. The method of claim 9 , wherein N is greater than 1.
15. A method of synthesizing chalcogenides comprising steps of:
creating n first sulfide/second sulfide/third sulfide stacks by:
depositing, via x number of cycles of atomic layer deposition, a first sulfide layer;
depositing, via y number of cycles of atomic layer deposition, a SnS 2 layer; and
depositing, via z number of cycles of atomic layer deposition, a third sulfide layer.
16. The method of claim 15 , wherein n is one and further comprising mixing the first sulfide layer, the SnS 2 layer, and the third sulfide layer.
17. The method of claim 15 , wherein n is greater than one.
18. A method of depositing SnS 2 on a substrate, comprising the steps of:
exposing the substrate to tetrakis(dimethylamido)Sn(IV) for about 1 second, then;
purging for about 20 seconds with an inert gas, then;
exposing the substrate to a H 2 S for about 1s; and
purging for about 20 seconds with nitrogen.