ZINC OXIDE MULTI-JUNCTION PHOTOVOLTAIC CELLS AND OPTOELECTRONIC DEVICES

• US 20100032008A1
• Filed: 06/04/2009
• Published: 02/11/2010
• Est. Priority Date: 12/11/2006
• Status: Abandoned Application

• Current Assignee: Key Trans Investments LLC (Intellectual Ventures LLC)
• Original Assignee: LumenZ, Inc
• Inventors: ADEKORE, Bunmi T.
• Application Number:
  US12/478,626
• Publication Number:
  US 20100032008A1
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/0256 Selenides
• CPC Class Codes: H01L 21/02562 Tellurides
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 31/0296 including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
• CPC Class Codes: H01L 31/0687 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/07 the potential barriers being only of the Schottky type
• CPC Class Codes: H01L 31/0725 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/073 comprising only AIIBVI compound semiconductors, e.g. CdS/CdTe solar cells
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/28 containing only elements of Group II and Group VI of the Periodic Table
• CPC Class Codes: H01L 33/285 characterised by the doping materials
• CPC Class Codes: H01S 5/04253 having specific optical properties, e.g. transparent electrodes
• CPC Class Codes: H01S 5/04256 characterised by the configuration
• CPC Class Codes: H01S 5/183 having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H01S 5/3095 Tunnel junction
• CPC Class Codes: H01S 5/347 : in AIIBVI compounds, e.g. ZnCdSe- laser
• CPC Class Codes: H01S 5/4093 : Red, green and blue [RGB] generated directly by laser action or by a combination of laser action with nonlinear frequency conversion
• CPC Class Codes: H01S 5/423 : having a vertical cavity
• CPC Class Codes: Y02E 10/543 : Solar cells from Group II-VI materials
• CPC Class Codes: Y02E 10/544 : Solar cells from Group III-V materials

Abstract

Devices and methods of fabrication of ZnO based single and multi-junction photovoltaic cells are disclosed. ZnO based single and multijunction photovoltaic cells, and other optoelectronic devices include p-type, n-type, and undoped materials of Zn_xA_1-xO_yB_1-y, wherein the alloy composition A and B, expressed by x and y, respectively, varies between 0 and 1. Alloy element A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and alloy element B is selected from a related elements including Te and Se. The selection of A, B, x and y, allows tuning of the material'"'"'s band gap. The band gap of the material may be selected to range between approximately 1.4 eV and approximately 6.0 eV. Zn_xA_1-xO_yB_1-y based tunnel diodes may be formed and employed in Zn_xA_1-xO_yB_1-y based multi-junction photovoltaic devices. Zn_xA_1-xO_yB_1-y based single and multi-junction photovoltaic devices may also include transparent, conductive heterostructures and highly doped contacts to ZnO based substrates.

Claims

1. A ZnO composition comprising Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

2. The ZnO composition of claim 1, wherein 0.6≦

x<

1 and 0.7<

y<

1.

3. The ZnO composition of claim 2, wherein A, B, x and y are selected to provide a semiconductor having a bandgap of less than or equal to about 1.9 eV.

4. The ZnO composition of claim 3, wherein A comprises Cd and B comprises Te.

5. The ZnO composition of claim 1, wherein the composition is a p-type conductor material.

6. The ZnO composition of claim 5, wherein the composition is doped with a p dopant selected from the group consisting of Au, Ag and K.

7. The ZnO composition of claim 1, wherein the composition is an n-type conductor material.

8. The ZnO composition of claim 7, wherein the composition is doped with an n dopant selected from the group consisting of Al, Ga, In.

9. A ZnO crystalline film comprising Zn_xA_1-xB_1-yO_y disposed on a substrate, where x can vary from 0 to 1 and 0<

y<

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

10. The ZnO crystalline film of claim 9, wherein 0.7<

y<

1.

11. The ZnO crystalline film of claim 9, wherein the layer is an epitaxy layer.

12. The ZnO crystalline film of claim 9, wherein the substrate is selected from the group consisting of ZnO, III-nitride, sapphire, silicon, ScAlMg, or glass substrates.

13. The ZnO crystalline film of claim 9, wherein each of x, y, A, and B is selected to provide a bandgap of less than about 1.9 eV.

14. The ZnO crystalline film of claim 9, wherein A comprises Cd and B comprises Te.

15. The ZnO crystalline film of claim 9, wherein the composition is a p-type conductor material.

16. The ZnO crystalline film of claim 15, wherein the composition is doped with a p dopant selected from the group consisting of Au, Ag and K.

17. The ZnO crystalline film of claim 9, wherein the composition is an n-type conductor material.

18. The ZnO crystalline film of claim 17, wherein the composition is doped with an n dopant selected from the group consisting of Al, Ga, In.

26. The semiconductor photovoltaic device of claim 11, wherein the gradient of the materials is selected to provide lattice matching among adjacent materials in the plurality of n-type materials.

27. The semiconductor photovoltaic device of claim 12, wherein the gradient of the materials is selected to provide lattice matching among adjacent materials in the plurality of p-type materials.

28. The semiconductor photovoltaic device of claim 13, wherein A and B are selected to provide a junction bandgap having efficient spectral response between approximately 2.0 eV and approximately 1.5 eV.

43. The semiconductor photovoltaic device of claim 16, further comprising electrical contacts for connecting to an outside circuit, said contacts selected from the group consisting of silver, gold, nickel, and platinum, intermetallics, amalgams and/or eutectics of silver, gold, platinum, and nickel, oxides of silver, and nickel, and transparent conducting oxides including indium tin oxide, zinc indium oxide, zinc tin oxide or conducting n-ZnO doped with aluminum, and/or indium, and/or gallium.

19. A semiconductor photovoltaic device having at least one junction comprising:

an n-type semiconductor material;

a p-type semiconductor material disposed in contact with the n-type semiconductor material;

wherein each of the n-type and p-type semiconductor materials comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), wherein A is selected from the group of related elements comprising Mg, Be, Ca, Sr, Ba, Mn, Cd, and In, wherein B is selected from the group of related elements comprising Te and Se, and wherein each of x, y, A, and B is selected to provide a junction bandgap corresponding to selected spectral range for absorption by the photovoltaic device.

20. The semiconductor photovoltaic device of claim 19, wherein the p-type semiconductor material comprises a semiconductor material doped with a dopant selected from the group of elements comprising:

Ag, Au, and K.

21. The semiconductor photovoltaic device of claim 19, wherein the n-type semiconductor material comprises a semiconductor material doped with a dopant selected from the group of elements comprising:

Al, In and As.

22. The semiconductor photovoltaic device of claim 19, wherein each of x, y, A, and B is selected to provide a junction bandgap of between approximately 6.0 eV and approximately 1.0 eV.

23. The semiconductor photovoltaic device of claim 19, further comprising a substrate of ZnO, the n-type doped semiconductor material disposed in contact with the substrate.

24. The semiconductor photovoltaic device of claim 19, wherein the n-type semiconductor material comprises a plurality of n-type materials of the form Zn_xA_1-xO_yB_1-y and wherein x and y are varied incrementally from a first of the plurality of n-type materials to a last of the plurality of n-type materials to form a gradient of materials.

25. The semiconductor photovoltaic device of claim 19, wherein the p-type semiconductor material comprises a plurality of p-type materials of the form Zn_xA_1-xO_yB_1-y and wherein x and y are varied incrementally from a first of the plurality of n-type materials to a last of the plurality of p-type materials to form a gradient of materials.

29. A semiconductor photovoltaic device comprising:

a plurality of semiconductor junctions, each comprising;

an n-type semiconductor material;

a p-type semiconductor material disposed in contact with the n-type semiconductor material;

wherein each of the n-type semiconductor material and the p-type semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), and wherein each of x, y, A, and B is selected to provide a bandgap for the semiconductor junction;

wherein the plurality of semiconductor junctions are selected to correspond to a selected spectral range for the semiconductor photovoltaic device.

30. The semiconductor photovoltaic device of claim 29, wherein A is selected from the group of related elements consisting of Mg, Be, Ca, Sr, Ba, Mn, Cd, and In, and wherein B is selected from the group of related elements consisting of Te and Se.

31. The semiconductor photovoltaic device of claim 29, wherein the plurality of semiconductor junctions is disposed on a substrate

32. The semiconductor photovoltaic device of claim 29, wherein a first of the plurality of semiconductor junctions comprises n-type and p-type semiconductor materials to provide a first bandgap and a second of the plurality of semiconductor junctions comprises n-type and p-type semiconductor materials to provide a second bandgap, the first bandgap being higher than the second bandgap.

33. The semiconductor photovoltaic device of claim 32 wherein the first semiconductor junction is disposed on the substrate and the second semiconductor junction is disposed on the first semiconductor junction.

34. The semiconductor photovoltaic device of claim 33 wherein the second semiconductor junction is disposed on the substrate and the first semiconductor junction is disposed on the second semiconductor junction.

35. The semiconductor photovoltaic device of claim 32, further comprising a resonant interband tunnel diode disposed between and in electrical communication with the first semiconductor junction and the second semiconductor junction.

36. The semiconductor photovoltaic device of claim 29, wherein each of x, y, A, and B is selected to provide a junction bandgap of between approximately 6.0 eV and approximately 1.0 eV.

37. The semiconductor photovoltaic device of claim 32, wherein for the first of the semiconductor junctions, each of x, y, A, and B is selected to provide a junction bandgap of between approximately 3.0 eV and approximately 4.0 eV and wherein for the second of the semiconductor junctions, each of x, y, A, and B is selected to provide a junction bandgap of between approximately 1.0 eV and approximately 3.0 eV.

38. The semiconductor photovoltaic device of claim 29, wherein the junctions range from higher bandgap to lower bandgap Zn_xA_1-xO_yB_1-y films.

39. The semiconductor photovoltaic device of claim 38, wherein the topmost Zn_xA_1-xO_yB_1-y film is the higher bandgap material.

40. The semiconductor photovoltaic device of claim 38, wherein the topmost Zn_xA_1-xO_yB_1-y film is the lower bandgap material.

41. The semiconductor photovoltaic device of claim 35, wherein the ZnO tunnel diodes comprise delta doped regions of n and p type carriers deposited between 100°

C. and 900°

C.

42. The semiconductor photovoltaic device of claim 35, wherein the ZnO resonant interband tunnel diodes comprising compounds of Zn_xA_1-xO_yB_1-y where x and y can vary from 0 to 1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

44. A method of making a photodiode comprising:

epitaxially growing a first p/n junction on a crystalline substrate in a CVD process in a continuous process, the first p/n junction comprising;

n-type semiconductor material;

a p-type semiconductor material, wherein each of the first doped semiconductor material and the second doped semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y (0≦

x≦

1) (0≦

y≦

1), and wherein each of x, y, A, and B is selected to provide a bandgap for the semiconductor junction,

by varying the composition of a vapor source of zinc, a vapor source of A, a vapor source of O and a vapor source of B.

45. The method of claim 44, further comprising:

epitaxially growing a second p/n junction in a CVD process in a continuous system, the first p/n junction comprising;

a second n-type semiconductor material;

a second a p-type semiconductor material, wherein each of the first doped semiconductor material and the second doped semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y (0≦

x≦

1) (0≦

y≦

1), and wherein each of x, y, A, and B is selected to provide a bandgap for the semiconductor junction,

by varying the composition of a vapor source of zinc, a vapor source of A, a vapor source of O and a vapor source of B.

46. The method of claim 44, further comprising:

epitaxially growing a third p/n junction in a CVD process in a continuous system, the second p/n junction comprising;

a third n-type semiconductor material;

a third a p-type semiconductor material, wherein each of the first doped semiconductor material and the second doped semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), and wherein each of x, y, A, and B is selected to provide a bandgap for the semiconductor junction,

by varying the composition of a vapor source of zinc, a vapor source of A, a vapor source of O and a vapor source of B.

47. The method of claim 45, further comprising:

epitaxially growing a a resonant interband tunnel diode after the epixtaixal growth of the first p/n junction and before the growth of the second p/n junction.

48. The method of claim 45, further comprising:

epitaxially growing a transparent electrical contact on the uppermost surface of the photodiode, the contact comprising a conducting oxides selected from the group consisting of indium tin oxide, zinc indium oxide, zinc tin oxide or conducting n-ZnO doped with aluminum, and/or indium, and/or gallium,

by varying the composition of a vapor source of zinc, a vapor source of Al, and/or In and/or Ga, and a vapor source of O.

49. A device, comprising:

at least one n-type semiconductor material;

at least one p-type semiconductor material disposed in contact with the n-type semiconductor material to form a semiconductor junction;

wherein each of the n-type semiconductor material and the p-type semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), and wherein each of x, y, A, and B is selected to provide a bandgap for the semiconductor junction.

50. The device of claim 49, wherein the device is selected from the group consisting of photodiodes, solar cells, optical detectors, optical emitters, light emitting diodes (LEDs), and laser diodes.

51. An optoelectronic device, comprising:

at least one n-doped semiconductor material;

at least one p-doped semiconductor material;

at least one semiconductor material disposed in contact with each of the n-doped semiconductor material and the p-doped semiconductor material;

wherein each of the n-doped semiconductor material, the p-doped semiconductor material, and the semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se, and wherein each of A, B, x and y is selected to provide a bandgap for the semiconductor material.

52. The optoelectronic device of claim 51, wherein the device is selected from the group consisting of photodiodes, optical emitters, light emitting diodes (LEDs), and laser diodes.

53. The optoelectronic device of claim 52, wherein the device comprises a LED and wherein each of A, B, x and y is selected to provide a bandgap of the semiconductor material less than approximately 1.9 eV.

54. The optoelectronic device of claim 53, wherein the LED emits light at a wavelength of greater than approximately 650 nm.

55. The optoelectronic device of claim 53, wherein A comprises Cd, B comprises Se, 0.7≦

x≦

1, and 0.9≦

y≦

1.

56. The optoelectronic device of claim 52, wherein the optical emitter comprises a vertical-cavity surface-emitting laser (VCSEL).

57. An optoelectronic device comprising a plurality of optical emitters, each optical emitter including:

at least one n-doped semiconductor material;

at least one p-doped semiconductor material;

at least one semiconductor material disposed in contact with each of the n-doped semiconductor material and the p-doped semiconductor material;

wherein each of the n-doped semiconductor material, the n-doped semiconductor material, and the semiconductor material comprises a compound of the form Zn_xA_1-xO_yB_1-y, (0≦

x≦

1) (0≦

y≦

1), A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se, wherein each of A, B, x and y is selected to provide a bandgap for the semiconductor material; and

wherein the bandgap for the semiconductor material of each optical emitter is selected to emit electromagnetic radiation at a discrete portion of the energy spectrum.

58. The optoelectronic device of claim 57, further comprising a waveguide for guiding electromagnetic radiation emitted by each of the plurality of optical emitters, the optoelectronic device emitting white RGB electromagnetic radiation.

59. An optoelectronic device, configured and arranged to emit light at one or more wavelengths, comprising a ZnO-based material of the composition Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

60. A light emitting diode (LED) comprising a ZnO-based material of the composition Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

61. A photodiode comprising a ZnO-based material of the composition Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

62. An optical detector comprising a ZnO-based material of the composition Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.

63. A laser diode comprising a ZnO-based material of the composition Zn_xA_1-xB_1-yO_y, where x can vary from 0 to 1 and 0≦

y≦

1, A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and B is selected from a related elements including Te and Se.