Process for manufacturing a solar cell

• US 7,071,018 B2
• Filed: 06/17/2002
• Issued: 07/04/2006
• Est. Priority Date: 06/19/2001
• Status: Expired due to Fees

• Current Assignee: BP Alternative Energy International Ltd. (BP PLC)
• Original Assignee: BP Solar Limited
• Inventors: Russell, Richard Walter John, Mason, Nigel Brunel
• Primary Examiner(s): SARKAR, ASOK K
• Application Number:
  US10/481,268
• Publication Number:
  US 20050074917A1
• Time in Patent Office: 1,478 Days
• Field of Search: 136/251, 136/252, 136/256, 257/431, 257/433, 257/436, 257/448, 257/457, 257/461, 438/22, 438/249, 438/368, 438/371, 438/372, 438/376, 438/392, 438/542, 438/549, 438/558, 438/560, 438/565, 438/567, 438/57
• US Class Current: 438/57
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Process for incorporating a back surface field into a silicon solar cell by depositing a layer of aluminium on the rear surface of the cell, sintering the aluminium at a temperature between 700 and 1000° C., exposing the cell to an atmosphere of a compound of Group V element and diffusing at a temperature of between 950 and 1000°C. so as to dope exposed p-type silicon surfaces with the Group V element. The step of exposing the cell to an atmosphere of a compound of a Group V element is carried separately from the step of sintering the aluminium layer, and subsequent to the step of depositing a layer of aluminium on the rear surface of the cell.

Claims

1. Process for incorporating a back surface field into a silicon solar cell, which comprises the steps of:

a) depositing a layer of aluminium on a rear surface of the cell;

b) sintering the aluminium layer at a sintering temperature of between 700 and 1000°

C.;

c) exposing the cell to an atmosphere of a compound of a Group V element, and diffusing at a temperature of between 950 and 1000°

C., so as to dope exposed p-type silicon surfaces with said Group V element,

wherein step (c) is carried out separately from step (b) and subsequent to step (a).

2. Process according to claim 1, wherein the sintering temperature in step (b) is between 850 and 1000°

C.

3. Process according to claim 1, wherein the duration of the sintering in step (b) no more than 30 minutes.

4. Process according to claim 1, wherein the Group V element is phosphorus or arsenic.

5. Process according to claim 1, wherein the compound of the Group V element is POCl₃.

6. Process according to claim 1, wherein doping of step c) is carried out at a temperature of between 960 and 1000°

C.

7. Process according to claim 1, wherein the exposed p-type silicon surfaces are in the grooves cut into the surface of the cell.

8. Process according to claim 1, wherein the silicon is monocrystalline.

9. Process according to claim 1, wherein the sintering temperature in step (b) is between 900 and 960°

C.

10. Process according to claim 1, wherein the duration of the sintering in step (b) no more than 10 minutes.

11. Process according to claim 1, wherein the aluminium is deposited to a thickness of 0.2 to 2.0 μ

m.