Photovoltaic device and process for producing the same

• US 6,242,686 B1
• Filed: 06/11/1999
• Issued: 06/05/2001
• Est. Priority Date: 06/12/1998
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nakano, Takanori, Kishimoto, Katsushi, Sannomiya, Hitoshi, Nomoto, Katsuhiko
• Primary Examiner(s): DIAMOND, ALAN D
• Application Number:
  US09/330,165
• Time in Patent Office: 725 Days
• Field of Search: 136/255, 136/249.TJ, 136/258.AM, 136/258.PC, 136/249.MS, 136/261, 257/464, 257/431, 257/53, 257/55, 257/463, 438/57, 438/74, 438/96, 438/97
• US Class Current: 136/255
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/076 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/204 including AIVBIV alloys, e.g. SiGe, SiC
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A photovoltaic device have a pin junction of a p-layer, an i-layer and an n-layer, wherein the p-layer includes a first p-layer and a second p-layer thereover, the first p-layer having a thickness of 5 nm or less and being uniformly doped with a p-type impurity, and the second p-layer being formed by decomposition of a gas which does not positively incorporate a p-type impurity.

Claims

1. A photovoltaic device comprising a pin junction of a player, an i-layer and an n-layer,

wherein the p-layer includes a first p-layer and a second p-layer thereover, the first p-layer having a thickness of 5 nm or less and being uniformly doped with a p-type impurity, and the second p-layer being formed by decomposition of a gas which does not positively incorporate a p-type impurity;

wherein each of the first p-layer and the second p-layer comprises one of (a) hydrogenated amorphous silicon (a-Si;

H), (b) hydrogenated amorphous germanium (a-Ge;

H), and (c) hydrogenated amorphous silicon germanium (a-SiGe;

H); and

wherein the first p-layer is formed directly on a transparent electrode.

2. A photovoltaic device according to claim 1, wherein the second p-layer is p-type with a p-type impurity derived from any of the preformed first p-layer and a residue remaining in an apparatus when the second p-layer is formed in the same apparatus as used for the first p-layer.

3. A photovoltaic device according to claim 1, wherein the first p-layer is doped predominantly with the p-type impurity while it is also doped with a smaller amount of an n-type impurity than the p-type imprity, and the content of the p-type impurity in the second p-layer becomes lower as the second player is closer to the i-layer.

4. A photovoltaic device according to claim 1, wherein the photovoltaic device includes plural pin junctions, and

wherein at least one p-layer adjacent to an n-layer includes a first p-layer which is doped predominantly with the p-type impurity while it is also doped with a smaller amount of an n-type impurity than the p-type impurity and which has a thickness of 5 nm or less, and a second p-layer in which the content of the p-type impurity becomes lower as the second p-layer is closer to the i-layer.

5. A photovoltaic device according to claim 4, wherein the at least one p-layer has a larger optical band gap on a side to the n-layer and a smaller optical band gap on a side to the i-layer.

6. A photovoltaic device according to claim 1, wherein the second p-layer comprises a plurality of layers having light absorption coefficients which are greater as the layers are closer to the i-layer.

7. A process for producing a photovoltaic device having a pin junction of a p-layer, an i-layer and an n-layer, the process comprising:

forming a first p-layers which has a thickness of 5 nm or less and is uniformly doped with a p-type impurity, directly on a transparent electrode;

forming a second p-layer by decomposition of a gas which does not positively incorporate a p-type impurity, thereby to obtain the second p-layer,

wherein each of the first p-layer and the second p-layer of the p-layer each comprises one of;

(a) hydrogenated amorphous silicon (a-Si;

H), (b) hydrogenated amorphous germanium (a-Ge;

H), and (c) hydrogenated amorphous silicon germanium (a-SiGe;

H); and

forming the i-layer and n-layer in this order.

8. A process according to claim 7, wherein the second player is p-type with a p-type impurity derived from any of the preformed first p-layer and a residue remaining in an apparatus when the second p-layer is formed in the same apparatus as used for the first p-layer.

9. A process according to claim 7, wherein a surface of the first p-layer is subjected to a plasma treatment after the first p-layer is formed.

10. A process according to claim 7, wherein when the second p-layer gains a thickness during formation thereof, a resulting surface of the second p-layer is subjected to a plasma treatment.

11. A process according to claim 9, wherein the plasma treatment is conducted in such a manner that the treatment time and/or power to be applied is/are decreased every time a predetermined thickness is gained.

12. The process according to claim 7, wherein the first p-layer and the second p-layer are formed in the same chamber of a film-forming apparatus.

13. The process according to claim 7, wherein the i-layer is formed in a different chamber of a film-forming apparatus from a chamber for forming the first p-layer and the second p-layer.

14. A photovoltaic device comprising a pin junction of a p-layer, an i-layer and an n-layer,

wherein the p-layer includes a first p-layer and a second p-layer thereover, the first p-layer having a thickness of 5 nm or less and being uniformly doped with a p-type impurity, and the second p-layer being formed by decomposition of a gas which does not positively incorporate a p-type impurity;

and

wherein the second p-layer comprises a plurality of layers having light absorption coefficients which are greater as the layers are closer to the i-layer.