Light scattering structures for thin-film solar cells and methods of making the same
The present disclosure relates to a method that includes contacting a surface of a first layer that includes a Group III element and a Group V element with a gas that includes HCl, where the first layer is positioned in thermal contact with a wafer positioned in a chamber of a reactor, and the contacting results in a roughening of the surface.
1. A method comprising, in order:
depositing onto a surface, by hydride vapor phase epitaxy (HVPE), an absorber layer comprising a Group III element and a Group V element;
depositing onto the absorber layer, by HVPE, a second layer comprising a Group III element and a Group V element comprising at least one of As or P;
contacting a surface of the second layer with a gas comprising HCl, at least one chloride precursor of the Group III element of the second layer, and at least one hydride precursor of the Group V element of the second layer, wherein the contacting results in a roughening of the surface of the second layer to a roughness between about 20 nm and about 100 nm; and
depositing a reflector layer directly onto the roughened surface of the second layer, wherein:
the absorber layer and the second layer are positioned in thermal contact with a wafer positioned in a chamber of a reactor.
2. The method of claim 1 , wherein the roughness is between 20 nm and 30 nm.
3. The method of claim 1 , wherein the Group III element of the second layer comprises at least one of gallium, indium, or aluminum.
4. The method of claim 3 , wherein the second layer comprises at least one of GaInP, GaInAsP, AlGaInP, or AlGaInAsP.
5. The method of claim 1 , wherein the wafer is maintained at a temperature between about 650° C. and about 800° C.
6. The method of claim 1 , wherein a partial pressure of the HCl is maintained at between about 0.001 Torr and about 1.0 Torr.
7. The method of claim 1 , wherein the contacting is maintained for a period of time between about 10 seconds and about 10 minutes.
8. The method of claim 1 , further comprising:
contacting HCl with a first liquid positioned in a first boat, resulting in the forming of a first intermediate gas; and
contacting HCl with a second liquid positioned in a second boat, resulting in the forming of a second intermediate gas, wherein:
the first intermediate gas and the second intermediate interact, resulting in the depositing of the second layer on the wafer.
9. The method of claim 8 , wherein the first liquid is gallium and the first intermediate gas comprises a first chloride precursor comprising GaCl.
10. The method of claim 8 , wherein the first liquid is indium and the second intermediate gas comprises a second chloride precursor comprising InCl.
11. The method of claim 1 , wherein the second layer has a first thickness between about 300 nm and about 1200 nm.
12. The method of claim 1 , wherein the absorber layer has a thickness between about 100 nm and about 500 nm.
13. The method of claim 1 , wherein the reflector layer comprises at least one of gold, silver, copper, or nickel.