SOLAR CELL AND METHOD OF FABRICATING THE SAME

• US 20100126569A1
• Filed: 10/20/2009
• Published: 05/27/2010
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Czang-Ho, Oh, Min-Seok, Jung, Seung-Jae, Park, Min, Shin, Myung-Hun, Lee, Byoung-Kyu, Lim, Mi-Hwa, Seo, Joon-Young, Nam, Yuk-Hyun
• Granted Patent: US 8,354,585 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/02363 of the semiconductor body itself, e.g. textured active layers
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/0745 comprising a AIVBIV heterojunction, e.g. Si/Ge, SiGe/Si or Si/SiC solar cells
• CPC Class Codes: H01L 31/0747 comprising a heterojunction of crystalline and amorphous materials, e.g. heterojunction with intrinsic thin layer
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

A solar cell includes: a semiconductor substrate having a first surface and a second surface opposite the first surface; uneven patterns disposed on at least one of the first surface and the second surface of the semiconductor substrate; a first impurity layer disposed on the uneven patterns and which includes a first part having a first doping concentration and a second part having a second doping concentration greater than the first doping concentration; and a first electrode which contacts the second part of the first impurity layer and does not contact the first part of the first impurity layer.

Claims

1. A solar cell comprising:

a semiconductor substrate having a first surface and a second surface opposite the first surface;

uneven patterns disposed on at least one of the first surface and the second surface of the semiconductor substrate;

a first impurity layer disposed on the uneven patterns and which comprises;

a first part having a first doping concentration; and

a second part having a second doping concentration which is greater than the first doping concentration; and

a first electrode which contacts the second part of the first impurity layer and does not contact the first part of the first impurity layer.

2. The solar cell of claim 1, further comprising an insulating layer disposed on the first part of the first impurity layer and which exposes the second part of the first impurity layer therethrough, wherein

the first impurity layer is uniformly disposed on the uneven patterns, and

the first electrode is disposed on the second part of the first impurity layer and the insulating layer.

3. The solar cell of claim 2, wherein the insulating layer has a light transmission rate of about 85% to about 93%.

4. The solar cell of claim 2, wherein the insulating layer has a thickness of about 3 μ

m to about 4 μ

m.

5. The solar cell of claim 1, wherein cross sections of the uneven patterns have substantially triangular shapes of a uniform size.

6. The solar cell of claim 5, wherein the uneven patterns have a cross sectional height of about 5 μ

m to about 7 μ

m.

7. The solar cell of claim 1, further comprising an intrinsic semiconductor layer disposed between the uneven patterns and the first impurity layer.

8. The solar cell of claim 7, wherein the intrinsic semiconductor layer has a thickness of about 1□

to 100□

.

9. The solar cell of claim 1, wherein

the first impurity layer is amorphous, and

the semiconductor substrate comprises one of monocrystalline and polycrystalline.

10. The solar cell of claim 1, wherein the first impurity layer has a thickness of about 50□

to about 100□

.

11. The solar cell of claim 1, further comprising:

a second impurity layer disposed on the second surface of the semiconductor substrate; and

a second electrode disposed on the second impurity layer,

wherein the uneven patterns are further disposed on the first surface of the semiconductor substrate.

12. The solar cell of claim 11, wherein

the semiconductor substrate has a first conductivity type, and

the first impurity layer has a second conductivity type opposite to the first conductivity type.

13. The solar cell of claim 12, wherein

the first electrode comprises a transparent electrode, and

the second electrode comprises one of a transparent electrode and a reflective electrode.

14. The solar cell of claim 12, wherein the semiconductor substrate and the first impurity layer have the first conductivity type.

15. The solar cell of claim 14, wherein

the first electrode comprises one of a transparent electrode and a reflective electrode, and

the second electrode comprises a transparent electrode.

16. The solar cell of claim 1, wherein

the uneven patterns comprise first uneven patterns disposed on the first surface of the semiconductor substrate and second uneven patterns disposed on the second surface of the semiconductor substrate which faces the first surface of the semiconductor substrate,

the semiconductor substrate has a first conductivity type,

the first impurity layer has a second conductivity type opposite to the first conductivity type, and

the first impurity layer and the first electrode are disposed on the first uneven patterns.

17. The solar cell of claim 16, further comprising:

a second impurity layer uniformly disposed on the second uneven patterns, the second impurity layer having the first conductivity type and comprising;

a first part having a third doping concentration; and

a second part having a fourth doping concentration which is greater than the third doping concentration; and

a second electrode which contacts the second part of the second impurity layer and does not contact the first part of the second impurity layer.

18. A method of fabricating a solar cell, the method comprising:

providing a semiconductor substrate having a first surface and a second surface opposite the first surface;

forming uneven patterns on at least one of the first surface and the second surface of the semiconductor substrate;

uniformly forming a first impurity layer, which comprises a first part having a first doping concentration and a second part having a second doping concentration greater than the first doping concentration, on the uneven patterns; and

forming a first electrode to contact the second part of the first impurity layer and to not contact the first part of the first impurity layer.

19. The method of claim 18, wherein the forming the uneven patterns comprises wet-etching the semiconductor substrate to form triangular shapes having substantially triangular cross sectional shapes, the triangular shapes having a uniform size.

20. The method of claim 18, wherein the uniformly forming the first impurity layer comprises:

uniformly disposing the first impurity layer, which has the first doping concentration, on the uneven patterns;

forming an insulating layer on the semiconductor substrate to expose at least a portion of the first impurity layer; and

forming the second part of the first impurity layer, which has the second doping concentration, by doping first impurities onto the exposed part of the first impurity layer.

21. The method of claim 20, wherein the forming the second part of the first impurity layer, which has the second doping concentration, comprises at least one of thermal diffusion, ion shower and ion implantation.

22. The method of claim 18, further comprising uniformly forming an intrinsic semiconductor layer on the uneven patterns before the uniformly forming the first impurity layer.

23. The method of claim 18, further comprising:

forming a second impurity layer on the second surface of the semiconductor substrate; and

forming a second electrode on the second impurity layer,

wherein the uneven patterns are formed on the first surface of the semiconductor substrate.

24. The method of claim 18, wherein the forming of the uneven patterns comprises:

forming first uneven patterns on the first surface of the semiconductor substrate; and

forming second uneven patterns on the second surface of the semiconductor substrate which faces the first surface of the semiconductor substrate, wherein

the first impurity layer and the first electrode are formed on the first uneven patterns,

the semiconductor substrate has a first conductivity type, and

the first impurity layer has a second conductivity type which is opposite to the first conductivity type.

25. The method of claim 24, wherein the uniformly forming the first impurity layer comprises:

disposing the first impurity layer, which has the first doping concentration, on the first uneven patterns;

forming a first insulating layer on the semiconductor substrate to expose at least a portion of the first impurity layer; and

forming the second part of the first impurity layer, which has the second doping concentration, by depositing first impurities on the at least a portion of the first impurity layer exposed through the first insulating layer.

26. The method of claim 25, further comprising forming a second impurity layer, which has the first conductivity type, and a second electrode on the second uneven patterns, wherein

the forming of the second impurity layer comprises:

uniformly disposing the second impurity layer, which has a third doping concentration, on the second uneven patterns;

forming a second insulating layer on the semiconductor substrate to expose at least a portion of the second impurity layer; and

forming a second part of the second impurity layer, which has a fourth doping concentration greater than the third doping concentration, by depositing second impurities on the at least a portion of the second impurity layer exposed through the second insulating layer.

27. The method of claim 26, wherein the second electrode contacts the second part of the second impurity layer and does not contact the first part of the first impurity layer.