Thin film solar cell

• US 20080078444A1
• Filed: 04/18/2007
• Published: 04/03/2008
• Est. Priority Date: 06/05/2006
• Status: Active Grant

• Current Assignee: IQE, PLC
• Original Assignee: Translucent Photonics, Inc. (Silex Systems Ltd.)
• Inventors: Atanackovic, Petar B.
• Granted Patent: US 7,928,317 B2
• Time in Patent Office: Days
• US Class Current: 136/256
• CPC Class Codes: H01L 31/06 characterised by potential barriers
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

Optimal structures for high efficiency thin film silicon solar energy conversion devices and systems are disclosed. Thin film silicon active layer photoelectron conversion structures using ion implantation are disclosed. Thin film semiconductor devices optimized for exploiting the high energy and ultraviolet portion of the solar spectrum at the earths surface are also disclosed. Solar cell fabrication using high oxygen concentration single crystal silicon substrates formed using in preference the CZ method are used advantageously. Furthermore, the present invention discloses optical coatings for advantageous coupling of solar radiation into thin film solar cell devices via the use of rare-earth metal oxide (REO_x), rare-earth metal oxynitride (REO_xN_y) and rare-earth metal oxy-phosphide (REO_xP_y) glasses and or crystalline material. The rare-earth metal is chosen from the group commonly known in the periodic table of elements as the lanthanide series.

Claims

1. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy,

such that the one or more layers of the large band gap material are contacting a layer of the small band gap material.

2. ) The device of claim 1 wherein said large band gap material has a band gap of at least 1.2 eV.

3. ) The device of claim 1 wherein said large band gap material comprises at least one rare-earth ion.

4. ) The device of claim 1 wherein said small band gap material comprises at least one from a group comprising Group IV, III-V, and II-VI semiconductors and combinations thereof.

5. ) The device of claim 1 wherein said large band gap material is single crystal.

6. ) The device of claim 1 wherein said substrate transmits a majority of said radiation impinging upon it to at least one of said one or more layers of a large band gap material.

8. ) The device of claim 6 wherein said composition of the layer proximate the upper surface comprises at least one rare-earth ion.

9. ) The device of claim 6 wherein said composition of the layer proximate the lower surface comprises at least one from a group comprising Group IV, III-V, and II-VI semiconductors and combinations thereof.

7. ) A device for converting radiation to electrical energy comprising:

a substrate; and

a layer for the converting comprising a lower surface in contact with the substrate and an upper surface wherein the composition of the layer varies from the upper surface to the lower surface from a composition with a large band gap to a composition with a lower band gap at the lower surface, wherein the large band gap material has a band gap of at least 1.2 eV at the upper surface.

10. ) A device for converting radiation to electrical energy comprising:

an active layer for the converting comprising at least a large band gap material layer and a small band gap material layer; and

an optically transparent conducting oxide over at least a portion of the surface of the active layer first receiving the radiation.

11. ) The device of claim 10 wherein the composition of said optically transparent conducting oxide comprises at least one rare-earth ion.

12. ) A device for converting radiation to electrical energy comprising:

an active region for the converting comprising at least one rare-earth metal ion, at least one elemental or compound semiconductor and at least one element chosen from a group comprising oxygen, nitrogen, and phosphorous.

13. ) The device of claim 12 wherein said rare-earth ion is in a +3 ionized state.

14. ) The device of claim 12 wherein a portion of said active region comprises minibands.

15. ) A device for converting radiation to electrical energy comprising:

a substrate;

an active layer for the converting radiation to electrical energy; and

interdigitated electrodes wherein the interdigitated electrodes have a spacing of less than about two microns, wherein the active layer comprises one or more rare-earth ions.

16. ) A device for converting radiation to electrical energy comprising:

an active layer for the converting radiation to electrical energy; and

a replacement substrate with electrodes connecting to the active layer, wherein the active layer comprises one or more rare-earth ions.

17. ) A device for converting radiation to electrical energy comprising:

an active layer for the converting radiation to electrical energy; and

a replacement substrate transparent to a majority of the radiation for converting, wherein the active layer comprises one or more rare-earth ions.

18. ) A device for converting radiation to electrical energy comprising:

a replacement substrate; and

an active layer for the converting radiation to electrical energy comprising at least one lateral p-n junction, wherein the active layer comprises one or more rare-earth ions.

19. ) A device for converting radiation to electrical energy comprising:

a replacement substrate comprising an electrical contact to the active layer; and

an active layer for the converting radiation to electrical energy comprising at least one lateral p-n junction, wherein the active layer comprises one or more rare-earth ions.

20. ) A device for converting radiation to electrical energy comprising:

a replacement substrate comprising an electrical contact to the active layer; and

an active layer for the converting radiation to electrical energy comprising at least two lateral p-n-p junctions.

21. ) A device for converting radiation to electrical energy as in claim 20 A device for converting radiation to electrical energy wherein the active layer comprises one or more rare-earth ions.

22. ) A device for converting radiation to electrical energy comprising:

a substrate;

an active layer for the converting radiation to electrical energy comprising at least one lateral p-n junctions; and

multiple p+ contacts to the active layer.

23. ) A device for converting radiation to electrical energy as in claim 22 wherein the active layer comprises one or more rare-earth ions.

24. ) A device for converting radiation to electrical energy comprising:

a substrate comprising an electrical contact to the active layer;

an active layer for the converting radiation to electrical energy comprising at least one lateral p-n junction; and

multiple p+ contacts to the active layer.

25. ) A device for converting radiation to electrical energy as in claim 24 wherein the active layer comprises one or more rare-earth ions.

26. ) A device for converting radiation to electrical energy comprising:

a substrate;

an active layer for the converting radiation to electrical energy comprising at least one vertical p-i-n structure.

27. ) A device for converting radiation to electrical energy as in claim 26 wherein the active layer comprises one or more rare-earth ions.

28. ) A device for converting radiation to electrical energy comprising:

a substrate;

an active layer for the converting radiation to electrical energy comprising at least one lateral p-i-n structure.

29. ) A device for converting radiation to electrical energy as in claim 28 wherein the active layer comprises one or more rare-earth ions.

30. ) An integrated device for converting radiation to electrical energy comprising:

a substrate;

one or more active layers for the converting radiation to electrical energy comprising multiple devices interconnected;

a plurality of devices for supplying a voltage; and

a plurality of devices for supplying a current.

31. ) An integrated device for converting radiation to electrical energy as in claim 30 wherein the active layer comprises one or more rare-earth ions.

32. ) A device for converting radiation to electrical energy comprising:

a first portion of a first conductivity type at a first level of doping;

a second portion of first conductivity type at a second level of doping less than the first,

wherein a first drift voltage is imposed across the second portion;

a third portion of first conductivity type at about the first level of doping;

a fourth portion of first conductivity type at about the second level of doping, wherein a second drift voltage is imposed across the fourth portion;

a fifth portion of second conductivity type at a third level of doping;

such that the second portion is a drift region and the fourth portion is an avalanche region and electrons undergo avalanche multiplication in the avalanche region based upon the first drift voltage imposed across the second portion and the second drift voltage imposed across the fourth portion.

33. ) A device for converting radiation to electrical energy as in claim 32 wherein at least one portion comprises one or more rare-earth ions.

34. ) A device for converting radiation to electrical energy as in claim 32 wherein the first and second drift voltages are set as a function of the energy of said radiation being converted.

35. ) The integrated device of claim 32 wherein at least said second and fourth portions comprise a semiconductor material comprising an indirect bandgap.

36. ) A device for converting radiation to electrical energy comprising:

a first portion of a first conductivity type at a first level of doping;

a second portion of first conductivity type at a second level of doping less than the first,

wherein a drift voltage is imposed across the second portion;

a third portion of second conductivity type at a third level of doping;

such that the second portion is a drift and avalanche region wherein electrons undergo avalanche multiplication based upon the drift voltage imposed across the second portion.

37. ) The device of claim 36 wherein at least said second portion comprises a semiconductor material comprising an indirect bandgap.

38. ) The device of claim 36 wherein at least one portion comprises one or more rare-earth ions.

39. ) The device of claim 36 wherein said drift voltage is set as a function of the energy of said radiation being converted.

40. ) The device of claim 36 wherein at least about 50% of said electrical energy is converted from radiation of wavelength 400 nm and shorter.

42. ) The method for producing a thin film according to claim 40 further comprising the step:

applying mechanical forces to separate the first and second substrates about the fracture depth after said heating.

43. ) The method for producing a thin film according to claim 40, wherein the first and second reactants are chosen from a group comprising hydrogen, oxygen, nitrogen, carbon, fluorine, helium and silicon.

45. ) The method for producing a thin film according to claim 43 further comprising the step:

applying mechanical forces to separate the first and second substrates about the fracture depth after said heating.

46. ) The method of claim 43 wherein an ion-exchange process is used for introducing said first and second reactant ions.

48. ) The method for producing a thin film according to claim 46 further comprising the step:

applying mechanical forces to separate the first and second substrates about the fracture depth after said heating.

41. ) A method for producing a thin film comprising:

providing a first substrate having a first surface and comprising a predetermined level of a first reactant therein;

introducing ions of a second reactant into the first surface, such that the ions are distributed about a predetermined fracture depth;

bonding a second substrate to the first surface of the first substrate; and

heating the first and second substrates to a temperature sufficient for the first and second reactants to combine.

44. ) A method for producing a thin film comprising:

providing a first substrate having a first surface;

introducing ions of a first and second reactant into the first surface, such that the ions are distributed about a predetermined fracture depth;

bonding a second substrate to the first surface of the first substrate; and

heating the first and second substrates to a temperature sufficient for the first and second reactants to combine.

47. ) A method for producing a thin film comprising:

providing a Czochralski grown substrate comprising a first surface and an oxygen content between about 1×

10¹⁷ and about 1×

10²¹ atoms/cm³;

introducing ions of a first composition into the first surface, such that the ions are distributed about a predetermined fracture depth;

bonding a second substrate to the first surface of the first substrate; and

heating the first and second substrates to a temperature sufficient for the oxygen and the introduced ions to combine.

49. ) A method for producing a thin film comprising:

providing a first substrate comprising a first surface;

depositing a sacrificial layer upon the first surface;

depositing one or more active layers upon the sacrificial layer;

depositing one or more first bonding layers upon the active layer;

providing a second substrate comprising a second surface;

depositing one or more second bonding layers upon the second surface;

bonding the one or more first bonding layers to the one or more second bonding layers; and

removing the sacrificial layer.

50. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from a group comprising rare-earth oxide (RE_xO_z), rare-earth germanium oxide (RE_xGe_yO_z), rare-earth silicon oxide (RE_xSi_yO_z), rare-earth-silicon-oxide-phosphide (RE_xSi_yO_zP_w), rare-earth-silicon-oxide-nitride (RE_xSi_yO_zN_w), rare-earth-silicon-oxide-nitride-phosphide (RE_xSi_yO_zN_wP_q).

51. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from rare-earth germanium oxide (RE_xGe_yO_z).

52. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from rare-earth silicon oxide (RE_xSi_yO_z).

53. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from rare-earth-silicon-oxide-phosphide (RE_xSi_yO_zP_w).

54. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from rare-earth-silicon-oxide-nitride (RE_xSi_yO_zN_w).

55. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the large band gap material chosen from rare-earth-silicon-oxide-nitride-phosphide (RE_xSi_yO_zN_wP_q).

56. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the small band gap material chosen from a group comprising rare-earth-silicon (RE_xSi_y), rare-earth-germanium (RE_xGe_y), rare-earth-phosphide (RE_xP_y), rare-earth-nitride (RE_xN_y),.

57. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the small band gap material chosen from rare-earth-germanium (RE_xGe_y).

58. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the narrow band gap material chosen from rare-earth-phosphide (RE_xP_y).

59. ) A device for converting radiation to electrical energy comprising:

a substrate;

one or more layers of a large band gap material; and

one or more layers of a small band gap material for converting radiation to electrical energy, such that the one or more layers of the large band gap material are contacting a layer of the small band gap material; and

the narrow band gap material chosen from rare-earth-nitride (RE_xN_y).