Multiple junction photovolatic devices and process for making the same

• US 20100300505A1
• Filed: 05/26/2009
• Published: 12/02/2010
• Est. Priority Date: 05/26/2009
• Status: Abandoned Application

• Current Assignee: Yung T. Chen
• Original Assignee: Yung T. Chen
• Inventors: Chen, Yung T.
• Application Number:
  US12/454,881
• Publication Number:
  US 20100300505A1
• Time in Patent Office: Days
• US Class Current: 136/244
• CPC Class Codes: H01L 21/02529 Silicon carbide
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 31/035218 the quantum structure being quantum dots
• CPC Class Codes: H01L 31/076 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/1812 including only AIVBIV alloys, e.g. SiGe
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

A photovoltaic device having multiple photoelectric conversion cells disposed in a tandem configuration and a chemical vapor deposition method for fabricating the same are disclosed. Each photoelectric conversion cell has a different band gap energy and includes a p-type semiconductor layer, an intrinsic semiconductor layer and an n-type semiconductor layer in sequential touching contact. Each semiconductor layer is formed of a nano-crystalline semiconductor containing silicon as a principal constituent. The semiconductor layer may be deposited by a novel chemical vapor deposition method which utilizes plasma and laser energies simultaneously to decompose a film forming gas, thereby forming a semiconductor film on a substrate. The chemical vapor deposition process may be carried out on a continuously conveying substrate, thereby permitting high throughput production of the photovoltaic device.

Claims

1. A photovoltaic device comprising:

a first photoelectric conversion cell including a first p-type semiconductor layer, a first intrinsic semiconductor layer and a first n-type semiconductor layer in sequential touching contact; and

a second photoelectric conversion cell including a second p-type semiconductor layer, a second intrinsic semiconductor layer and a second n-type semiconductor layer in sequential touching contact,

wherein said first cell has a higher band gap energy than said second cell, said semiconductor layers of said cells are formed of nano-crystalline semiconductors containing silicon as a principal constituent.

2. The photovoltaic device of claim 1, wherein said first cell has a band gap energy in the range of about 1.6 eV to about 1.9 eV and said second cell has a band gap energy in the range of about 0.7 eV to about 1.2 eV.

3. The photovoltaic device of claim 1, wherein:

said first p-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said first intrinsic semiconductor layer is formed of nc-Si_1-x-yC_xGe_y;

H, where x ranges from about 0.3 to about 0.4 and y ranges from about 0.1 to about 0.3;

said first n-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said second p-type semiconductor layer is formed of nc-Si;

H;

said second intrinsic semiconductor layer is formed of nc-Si;

H; and

said second n-type semiconductor layer is formed of nc-Si;

H.

4. The photovoltaic device of claim 1, wherein:

said first p-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said first intrinsic semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from about 0.3 to about 0.5;

said first n-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said second p-type semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one;

said second intrinsic semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one; and

said second n-type semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one.

5. The photovoltaic device of claim 1, wherein:

said first p-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said first intrinsic semiconductor layer is formed of a plurality of alternating layers of nc-Si_1-xC_x;

H and nc-Si_1-yGe_y;

H, where x and y range from more than zero to less than one;

said first n-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said second p-type semiconductor layer is formed of nc-Si;

H;

said second intrinsic semiconductor layer is formed of nc-Si;

H; and

said second n-type semiconductor layer is formed of nc-Si;

H.

6. A triple junction photovoltaic device comprising:

a first photoelectric conversion cell including a first p-type semiconductor layer, a first intrinsic semiconductor layer and a first n-type semiconductor layer in sequential touching contact;

a second photoelectric conversion cell including a second p-type semiconductor layer, a second intrinsic semiconductor layer and a second n-type semiconductor layer in sequential touching contact; and

a third photoelectric conversion cell including a third p-type semiconductor layer, a third intrinsic semiconductor layer and a third n-type semiconductor layer in sequential touching contact,

wherein said first cell has a higher band gap energy than said second cell, said second cell has a higher band gap energy than said third cell, said semiconductor layers of said cells are formed of nano-crystalline semiconductors containing silicon as a main constituent.

7. The photovoltaic device of claim 6, wherein said first cell has a band gap energy in the range of about 1.7 eV to about 2.0 eV, said second cell has a band gap energy in the range of about 1.4 eV to about 1.6 eV and said third cell has a band gap energy in the range of about 0.7 eV to about 1.2 eV.

8. The photovoltaic device of claim 6, wherein said first p-type semiconductor layer, said first intrinsic semiconductor layer and said first n-type semiconductor layer of said first cell are formed of Si_1-xC_x:

H, where x ranges from more than zero to less than one.

9. The photovoltaic device of claim 8, wherein:

said second p-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said second intrinsic semiconductor layer is formed of nc-Si_1-x-yC_xGe_y;

H, where x ranges from about 0.25 to about 0.35 and y ranges from about 0.15 to about 0.35;

said second n-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said third p-type semiconductor layer is formed of nc-Si;

H;

said third intrinsic semiconductor layer is formed of nc-Si;

H; and

said third n-type semiconductor layer is formed of nc-Si;

H.

10. The photovoltaic device of claim 8, wherein:

said second p-type semiconductor layer is formed of nc-Si;

H;

said second intrinsic semiconductor layer is formed of nc-Si;

H;

said second n-type semiconductor layer is formed of nc-Si;

H;

said third p-type semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one;

said third intrinsic semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one; and

said third n-type semiconductor layer is formed of nc-Si_1-xGe_x;

H, where x ranges from more than zero to less than one.

11. The photovoltaic device of claim 8, wherein:

said second p-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said second intrinsic semiconductor layer is formed of a plurality of alternating layers of nc-Si_1-xC_x;

H and nc-Si_1-yGe_y;

H, where x and y range from more than zero to less than one;

said second n-type semiconductor layer is formed of nc-Si_1-xC_x;

H, where x ranges from more than zero to less than one;

said third p-type semiconductor layer is formed of nc-Si;

H;

said third intrinsic semiconductor layer is formed of nc-Si;

H; and

said third n-type semiconductor layer is formed of nc-Si;

H.

12. A method for depositing a nano-crystalline semiconductor layer containing silicon as a principal constituent for a photoelectric conversion cell, the method comprising the steps of:

supporting a substrate in a reaction chamber;

introducing a film forming gas into said reaction chamber; and

generating a plasma in said reaction chamber by ionizing said film forming gas for decomposing said film forming gas while simultaneously emitting a laser into said reaction chamber through an incidence window for decomposing said film forming gas, thereby forming a film on said substrate.

13. The method of claim 12, wherein said laser is in the form of a sheet and passes in parallel with said substrate along a plane spaced apart therefrom.

14. The method of claim 12, further comprising the step of irradiating the semiconductor film on the substrate surface with an excimer laser, thereby improving the film crystallinity.

15. The method of claim 12, wherein said substrate is continuously conveyed in said reaction chamber during the film forming process.

16. The method of claim 15, further comprising the step of heating said substrate to a temperature in the range of about 250°

C. to about 500°

C. prior to introducing said film forming gas into said reaction chamber.

17. The method of claim 15, wherein said laser is in the form of a sheet and passes in parallel with said substrate along a plane spaced apart therefrom.

18. The method of claim 15, wherein said laser is in the form of at least one beam and passes in parallel with said substrate along a plane spaced apart therefrom.

19. The method of claim 15, wherein said film forming gas comprises gaseous hydrogen and a silicon containing gaseous compound selected from the group consisting of SiH₄, Si₂H₆, Si₃H₈, SiF₄, SiCl₄, SiH₃CH₃, Si₂(CH₃)₆, H₂SiCl₂ and HSiCl₃.

20. The method of claim 15, wherein an inert gas is blown against said incidence window for preventing clouding of said incidence window during film formation process.