Solar cell and method for producing such a cell

• US 6,316,716 B1
• Filed: 05/09/2000
• Issued: 11/13/2001
• Est. Priority Date: 05/11/1999
• Status: Expired due to Term

• Current Assignee: AZUR SPACE Solar Power GmbH (5N Plus, Inc.)
• Original Assignee: Angewandte Solarenergie--Ase GmbH
• Inventors: Hilgrath, Just
• Primary Examiner(s): DIAMOND, ALAN D
• Application Number:
  US09/567,153
• Time in Patent Office: 553 Days
• Field of Search: 136/249.TJ, 136/255, 136/256, 136/262, 257/437, 257/449, 257/461, 438/74, 438/92, 438/93
• US Class Current: 136/255
• CPC Class Codes: H01L 2224/4918 being disposed on at least two different sides of the body, e.g. dual array
• CPC Class Codes: H01L 27/1421 comprising bypass diodes integrated or directly associated with the device, e.g. bypass diode integrated or formed in or on the same substrate as the solar cell
• CPC Class Codes: H01L 31/0687 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/0693 the devices including, apart from doping material or other impurities, only AIIIBV compounds, e.g. GaAs or InP solar cells
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A solar cell includes a substrate carrier for current generating photoactive layers that include at least one front layer and one layer toward the substrate of different polarities, a front contact, at least one back contact and an integral protective diode which has a polarity opposite the solar cell integrated in and disposed on a front side of the solar cell and including at least one diode semiconductor layer. A tunnel diode extends between the photoactive layers and a region of the substrate toward the front, the tunnel diode being recessed adjacent the protective diode. The region of the substrate toward the front, or a layer toward the front applied to or formed by the front, together with a photoactive layer of corresponding polarity toward the front, make up the at least one diode semiconductor layer of the protective diode.

Claims

1. A solar cell comprising:

a substrate carrier for current generating photoactive layers that include at least one front layer and one layer toward the substrate of different polarities;

a front contact;

at least one back contact,

an integral protective diode which has a polarity opposite the solar cell integrated in and disposed on a front side of the solar cell and including at least one diode semiconductor layer; and

a tunnel diode extending between the photoactive layers an a region of the substrate toward the front, the tunnel diode being recessed adjacent the protective diode, and the region of the substrate toward the front, or a layer toward the front applied to or formed by the front, together with a photoactive layer of corresponding polarity toward the front, making up the at least one diode semiconductor layer of the protective diode.

2. The solar cell of claim 1, wherein a region of the protective diode that forms the at least one diode semiconductor layer extends in spaced-apart fashion from the photoactive layers.

3. The solar cell of claim 1, wherein the protective diode is a Schottky diode, MIS contact diode, P-N diffused contact diode, or metal-alloy contact diode.

4. The solar cell of claim 1, wherein the photoactive layers of the solar cell are separated from the protective diode, or metallizing thereof, by an electrically insulating layer.

5. The solar cell of claim 4, wherein the metallizing of the protective diode extends at least intermittently along the electrically insulating layer.

6. The solar cell of claim 4, wherein the metalizing of the protective diode extends along the electrically insulating layer as far as the front contact of the solar cell.

7. The solar cell of claim 4, wherein the front contact of the solar cell extends regionally along the electrically insulating layer and is joined directly to the metallizing of the protective diode.

8. The solar cell of claim 4, additionally comprising an electrically conductive connector extending from the front contact and/or the metallizing and leading to a back contact of a further solar cell.

9. The solar cell of claim 1, wherein the solar cell is a cascade solar cell, having at least first and second photoactive layers toward the front and toward the substrate, respectively, and that an intermediate semiconductor layer therebetween having polarity corresponding to the photoactive layer toward the front and forming the diode semiconductor layer extends between second photoactive layers toward the substrate and the substrate.

10. The solar cell of claim 9, wherein a tunnel diode is disposed between respective pairs of photoactive layers that form photoactive cells.

11. The solar cell of claim 1, wherein the substrate has a polarity opposite to the photoactive layer toward the front, and the tunnel diode extends between an intermediate semiconductor layer that forms the diode semiconductor layer and the substrate.

12. The solar cell of claim 11, wherein the substrate, in a region toward the front, comprises a p-n junction, over which the intermediate semiconductor layer forming the diode semiconductor layer extends, and

wherein on the intermediate layer, outside the protective diode, a second tunnel diode and the photoactive layers disposed on the tunnel diode are disposed.

13. A method for producing a solar cell having an integral protective diode which has a polarity opposite the solar cell and includes at least one diode semiconductor layer, the solar cell comprising at least one back contact, a substrate carrier for photoactive layers that include at least one front layer and one layer toward the substrate of different polarities, and a front contact, comprising the steps of:

applying or forming an intermediate semiconductor layer that forms the at least one diode semiconductor layer on or comprising a region toward the front of the substrate and having a polarity corresponding to the photoactive layer toward the front of the solar cell;

applying or forming a tunnel diode on or comprising the intermediate semiconductor layer;

applying or forming the photoactive layers on the substrate and front sides;

regionally laying the intermediate semiconductor layer bare; and

forming the protective diode having the polarity opposite the solar cell using the bared region of the intermediate semiconductor layer, by means of indirect or direct application of a metallizing thereon, and ensuing connection to the front contact.

14. The method of claim 13, wherein after the regional baring of the intermediate semiconductor layer, the front contact is disposed on the photoactive layer toward the front.

15. The method of claim 14, wherein the metallizing is electrically conductively connected to the front contact or is connected via an electrically conductive connector, which originates at the front contact and is connected to the back contact of a further solar cell.

16. The method of claim 13, wherein a shoulder is formed by vertical etching between the region of the intermediate semiconductor layer to be laid bare and the photoactive layers on the front and substrate sides.

17. The method of claim 16, wherein an electrically insulating layer is formed along the shoulder extending from the photoactive layer toward the front as far as the bared region of the intermediate semiconductor layer.

18. The method of claim 13, wherein the protective diode is a Schottky diode, MIS contact diode, p-n contact diode or metal-alloy diode.

19. The method of claim 13, wherein a p-n junction is formed on the front of the substrate, on which the intermediate semiconductor layer extends.

20. The method of claim 13, wherein a plurality of pairs of photoactive layers are applied to the intermediate semiconductor layer, and one tunnel diode extends between each of the respective pairs of photoactive layers.

21. The method of claim 13, wherein at least one of the layers that form the tunnel diode, the photoactive layers and the intermediate semiconductor layer are produced by epitaxial growth.