Multi-nary group IB and VIA based semiconductor
Methods and devices are provided for forming multi-nary semiconductor. In one embodiment, a method is provided comprising of depositing a precursor material onto a substrate, wherein the precursor material may include or may be used with an additive to minimize concentration of group IIIA material such as Ga in the back portion of the final semiconductor layer. The additive may be a non-copper Group IB additive in elemental or alloy form. Some embodiments may use both selenium and sulfur, forming a senary or higher semiconductor alloy. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
1. An optoelectronic device, comprising
a thin film absorber layer consisting essentially of: silver (Ag), copper (Cu), indium (In), gallium (Ga), selenium (Se), and sulfur (S);
wherein the absorber layer is characterized by an Ag/(Ag+Cu) ratio which is less than about 0.5.
2. The device of claim 1 , wherein the device exhibits at least about 10% conversion efficiency under AM 1.5G illumination.
3. The device of claim 1 , wherein the device exhibits at least about 11% conversion efficiency under AM 1.5G illumination.
4. The device of claim 1 , wherein the device exhibits at least about 12% conversion efficiency under AM 1.5G illumination.
5. The device of claim 1 , wherein the device exhibits at least about 13% conversion efficiency under AM 1.5G illumination.
6. The device of claim 1 , wherein the device exhibits at least about 14% conversion efficiency under AM 1.5G illumination.
7. The device of claim 1 , wherein the device exhibits at least about 15% conversion efficiency under AM 1.5G illumination.
8. The device of claim 1 , wherein the device exhibits at least about 16% conversion efficiency under AM 1.5G illumination.
9. The device of claim 1 , wherein the device exhibits at least about 17% conversion efficiency under AM 1.5G illumination.
10. The device of claim 1 , wherein the thin film absorber layer is formed on a base, wherein an oxygen content of the absorber layer at a surface region of the absorber layer is reduced compared to another thin film absorber layer comprising Ag, Cu, In, Ga, and Se that is formed in substantially the same manner as the thin film absorber layer comprising Ag, Cu, In, Ga, Se, and S.
11. The device of claim 1 , wherein the thin film absorber layer includes a surface region, a bulk region and a transition region disposed between the surface region and the bulk region, wherein a transition region Ag/(Ag+Cu) molar ratio in the transition region is higher than a surface region Ag/(Ag+Cu) ratio in the surface region.
12. The device of claim 11 , wherein the surface region is characterized by a thickness of less than about 300 nm, a Ga/(Ga+In) molar ratio that is in the range of about 0 to about 0.3, a S/(Se+S) molar ratio that is in the range of about 0.1 to about 0.7, and a Ag/(Ag+Cu) molar ratio that is in the range of about 0 to about 0.4.
13. The device of claim 11 , wherein the surface region is characterized by a thickness of less than about 300 nm, a surface region Ga/(Ga+In) molar ratio within the surface region in the range of 0 to about 0.3.
14. The device of claim 11 , wherein the bulk region is characterized by an average bulk region Ga/(Ga+In) molar ratio of about 0.5 or less.
15. The device of claim 11 , wherein the bulk region is at least 400 nm thick.
16. The device of claim 11 , wherein a surface region S/(S+Se) molar ratio in the surface region is greater than a surface region Ag/(Ag+Cu) ratio in the surface region.
17. The device of claim 11 , wherein an amount of silver in the absorber layer is large enough to bring gallium towards a surface of the thin film absorber layer.
18. The device of claim 1 , wherein the sulfur changes a bandgap in a surface region of the absorber layer.