Precursor containing copper indium and gallium for selenide (sulfide) compound formation
View Patent ↗The present invention relates to systems and methods for preparing metallic precursor thin films for the growth of semiconductor compounds to be used for radiation detector and solar cell fabrication. In one aspect, there is provided a method of efficiently using expensive materials necessary for the making of solar cells.
1. A method of forming a Cu(In,Ga)(S,Se)2 semiconductor layer on a base comprising;
growing a conductive layer on a substrate thus forming a base;
depositing on the conductive layer a substantially metallic film comprising copper;
electroplating a gallium film over the substantially metallic film;
electroplating an indium film over the gallium film, thereby providing a precursor stack that has an indium-rich top surface with a melting temperature of higher than that of gallium, wherein the step of electroplating the indium film is carried out at a temperature below the melting temperature of gallium; and
reacting the precursor stack with at least one of selenium and sulfur.
2. The method according to claim 1 wherein the conductive layer comprises Mo and the step of depositing uses a physical vapor deposition technique.
3. The method according to claim 2 wherein the substantially metallic film is a pure copper film.
4. The method according to claim 3 wherein the physical vapor deposition technique is sputtering.
5. The method according to claim 1 wherein the step of depositing uses electroplating.
6. The method according to claim 5 wherein the substantially metallic film is a pure copper film.
7. The method according to claim 1 wherein during the step of electroplating the indium film, the gallium film maintains a solid form.
8. The method according to claim 1 wherein the step of electroplating the indium film is carried out at a bath temperature of 10-15° C.