Methods of forming a conductive transparent oxide film layer for use in a cadmium telluride based thin film photovoltaic device

• US 8,043,954 B1
• Filed: 03/30/2010
• Issued: 10/25/2011
• Est. Priority Date: 03/30/2010
• Status: Expired due to Fees

• Current Assignee: First Solar Incorporated
• Original Assignee: PrimeStar Solar, Inc. (GE Aerospace)
• Inventors: Feldman-Peabody, Scott Daniel
• Primary Examiner(s): Sarkar; Asok
• Application Number:
  US12/750,116
• Publication Number:
  US 20110244621A1
• Time in Patent Office: 574 Days
• Field of Search: 136/256, 136/260, 136/264, 257/E21.159, 438/85, 438/98, 438/608, 438/609
• US Class Current: 438/609
• CPC Class Codes: C23C 14/0057 using reactive gases other than O2, H2O, N2, NH3 or CH4
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/34 Sputtering
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02472 Oxides
• CPC Class Codes: H01L 21/02483 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/02562 Tellurides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 31/073 comprising only AIIBVI compound semiconductors, e.g. CdS/CdTe solar cells
• CPC Class Codes: H01L 31/1836 comprising a growth substrate not being an AIIBVI compound
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/543 Solar cells from Group II-VI materials
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Methods are generally provided for forming a conductive oxide layer on a substrate. In one particular embodiment, the method can include sputtering a transparent conductive oxide layer on a substrate from a target (e.g., including cadmium stannate) in a sputtering atmosphere comprising cadmium. The transparent conductive oxide layer can be sputtered at a sputtering temperature of about 100° C. to about 600° C. Methods are also generally provided for manufacturing a cadmium telluride based thin film photovoltaic device.

Claims

1. A method for forming a conductive oxide layer on a substrate, the method comprising:

sputtering a target in a sputtering atmosphere to deposit a transparent conductive oxide layer on a substrate, wherein the target comprises cadmium stannate, and wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100°

C. to about 600°

C.; and

,

during sputtering, adding a cadmium gas source to the sputtering atmosphere to provide an increased amount of cadmium to the sputtering atmosphere than supplied by the target.

2. The method as in claim 1, wherein the cadmium gas source comprises an organo-cadmium gas.

3. The method as in claim 1, wherein the cadmium gas source comprises dimethyl cadmium.

4. The method as in claim 1, wherein the sputtering atmosphere further comprises an inert gas.

5. The method as in claim 4, wherein the inert gas is argon.

6. The method as in claim 1, wherein the sputtering atmosphere further comprises oxygen.

7. The method as in claim 1, wherein the sputtering atmosphere has a pressure of about 1 mTorr to about 100 mTorr.

8. The method as in claim 1, wherein the cadmium gas source constitutes about 0.1% to about 25% by volume of the sputtering atmosphere.

9. The method as in claim 1, wherein the cadmium gas source about 1% to about 15% by volume of the sputtering atmosphere.

10. The method as in claim 1, wherein the transparent conductive oxide layer has a thickness of about 100 nm to about 1 μ

m.

11. The method as in claim 1, wherein the transparent conductive oxide layer has a thickness of about 150 nm to about 400 nm.

12. The method as in claim 1, wherein the sputtering temperature is about 150°

C. to about 300°

C.

13. The method as in claim 1, wherein the sputtering temperature is about 175°

C. to about 250°

C.

14. The method as in claim 1, wherein the cadmium gas source constitutes about 0.1% to about 25% by volume of the sputtering atmosphere.

15. A method for manufacturing a cadmium telluride based thin film photovoltaic device, the method comprising:

sputtering a target in a sputtering atmosphere to deposit a transparent conductive oxide layer on a substrate, wherein the target comprises cadmium stannate, and wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100°

C. to about 600°

C.; and

,

during sputtering, adding a cadmium gas source to the sputtering atmosphere to provide an increased amount of cadmium to the sputtering atmosphere than supplied by the target;

forming a resistive transparent buffer layer over the transparent conductive oxide layer;

forming a cadmium sulfide layer over the resistive transparent layer; and

,

forming a cadmium telluride layer over the cadmium sulfide layer.

16. The method as in claim 15, wherein the cadmium gas source comprises an organo-cadmium gas.

17. The method as in claim 15, wherein the sputtering temperature is about 150°

C. to about 300°

C.

18. The method as in claim 15, wherein the cadmium gas source comprises an organo-cadmium gas, the sputtering atmosphere further comprising an inert gas.

19. The method as in claim 18, wherein the organo-cadmium gas comprises dimethyl cadmium.