Amorphous semiconductors equivalent to crystalline semiconductors produced by a glow discharge process

• US 4,226,898 A
• Filed: 03/16/1978
• Issued: 10/07/1980
• Est. Priority Date: 03/16/1978
• Status: Expired due to Term

• Current Assignee: United Solar Systems Corp.
• Original Assignee: Energy Conversion Devices
• Inventors: Ovshinsky, Stanford R., Madan, Arun
• Primary Examiner(s): Smith, John D.
• Application Number:
  US05/887,353
• Time in Patent Office: 936 Days
• Field of Search: 148/1.5, 148/91, 357/2, 357/13, 357/20, 357/63, 427/53, 427/85, 427/86, 427/39, 427/87
• US Class Current: 438/483
• CPC Class Codes: C23C 16/24 Deposition of silicon only
• CPC Class Codes: C23C 16/28 Deposition of only one other non-metal element
• CPC Class Codes: C23C 16/50 using electric discharges generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34
• CPC Class Codes: G03G 5/08235 comprising three or four silicon-based layers
• CPC Class Codes: G03G 5/0825 comprising five or six silicon-based layers
• CPC Class Codes: G03G 5/08278 Depositing methods
• CPC Class Codes: H01L 21/02425 Conductive materials, e.g. metallic silicides
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/02592 amorphous
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 31/20 such devices or parts thereof comprising amorphous semiconductor materials
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 148/061 Gettering-armorphous layers

Abstract

A method of making an amorphous semiconductor film or the like having desirable photoconductive and/or other properties comprises depositing on a substrate a solid amorphous semiconductor film including at least one element, by glow discharge decomposition of a compound containing said at least one element and at least one alterant element in an atmosphere separately containing at least one different alterant element, wherein the plurality of different alterant elements comprise at least fluorine and are incorporated in said amorphous semiconductor film during the deposition thereof yielding an altered amorphous semiconductor material having reduced density of localized states in the energy gap thereof so that greatly increased diffusion lengths for solar cell application are obtained and modifiers or dopants can be effectively added to produce p-type or n-type amorphous semiconductor films so that the films function like similar crystalline semiconductors.

Claims

1. The method of making a semiconductor film comprising a solid amorphous semiconductor host matrix including at least one element and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix including at least one element by glow discharge decomposition of a compound containing said at least one element and at least one alterant element in a partial vacuum having an atmosphere separately containing at least one different alterant element and not derived from the compound, wherein said different at least one alterant elements of said compound and separately contained in said atmosphere comprise at least fluorine and are incorporated in said amorphous semiconductor host matrix during deposition thereof yelding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

2. The method as defined in claim 1 wherein said alterant elements are made reactive by the glow discharge.

3. The method as defined in claim 1 comprising controlling the relative amounts of said compound and said alterant elements.

4. The method as defined in claim 1 comprising controlling the temperature of deposition of the solid amorphous semiconductor host matrix.

5. The method as defined in claim 1 wherein said alterant elements comprise at least hydrogen and fluorine.

6. The method as defined in claim 1 wherein said alterant elements comprise at least rare earth elements, transition metal elements, chlorine, boron or carbon.

7. The method as defined in claim 1 wherein said at least one element of the amorphous semiconductor host matrix comprises silicon.

8. The method as defined in claim 1 wherein said at least one element of the amorphous semiconductor host matrix comprises germanium.

9. The method as defined in claim 1 wherein said at least one element of the amorphous semiconductor host matrix comprises a Group III element.

10. The method as defined in claim 1 wherein said at least one element of the amorphous semiconductor host matrix comprises a Group V element.

11. The method as defined in claim 1 wherein said at least one element of the amorphous semiconductor host matrix comprises a Group VI element.

12. The method as defined in claim 1 wherein the compound comprises silicon tetrafluoride and wherein the alterant element separately contained in the atmosphere comprises hydrogen.

13. The method as defined in claim 1 wherein the atmosphere for the glow discharge decomposition separately contains a modifier element which is incorporated in said amorphous semiconductor host matrix during formtion thereof yielding a modified amorphous semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap.

14. The method as defined in claim 13 wherein the modified amorphous semiconductor material is such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

15. The method as defined in claim 14 wherein the modifier element is obtained from arsine during the glow discharge deposition of the amorphous semiconductor host matrix.

16. The method as defined in claim 14 wherein the modifier element is obtained from phosphine, ammonia, Ga(CH₃)₃ or (C₂ H₅)₃ Al.

17. The method as defined in claim 13 wherein said modifier element is made reactive by the glow discharge.

18. The method as defined in claim 13 wherein said alterant elements and said modifier element are made reactive by the glow discharge.

19. The method as defined in claim 13 comprising controlling the relative amounts of said compound and said modifier element.

20. The method as defined in claim 13 wherein said modifier element comprises Group V elements or Group III elements for p or n-type conduction.

21. The method as defined in claim 13 wherein said modifier element comprises zinc, copper, gold, silver or manganese for enhancing photoconductivity.

22. The method as defined in claim 13 wherein said modifier element comprises transition metal elements for increasing electrical conductivity.

23. The method of making a semiconductor film comprising a solid amorphous semiconductor host matrix including at least one element and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix including at least one element by glow discharge decomposition of a plurality of compounds, each containing said at least one element and at least one different alterant element, wherein said different at least one alterant elements of said compounds comprise at least fluorine and are incorporated in said amorphous semiconductor host matrix during deposition thereof yeilding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

24. The method as defined in claim 23 wherein said alterant elements are made reactive by the glow discharge.

25. The method as defined in claim 23 wherein said alterant elements comprise at least hydrogen.

26. The method as defined in claim 23 wherein the plurality of compounds comprise silicon tetrafluoride and silane.

27. The method as defined in claim 23 wherein the atmosphere for the glow discharge decomposition separately contains a modifier element which is incorporated in said amorphous semiconductor host matrix during the formation thereof yielding a modified amorphous semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap, such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

28. The method as defined in claim 27 wherein said modifier element is made reactive by the glow discharge.

29. The method of making a semiconductor film comprising a solid amorphous semiconductor host matrix including at least one element and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix including at least one element by glow discharge decomposition of a plurality of compounds, each containing said at least one element and at least one alterant element, in a partial vacuum having an atmosphere separately containing at least one different alterant element and not derived from the compounds, wherein said different at least one alterant elements of said compounds and separately contained in said atmosphere comprise at least fluorine and are incorporated in said amorphous semiconductor host matrix during deposition thereof yielding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

30. The method as defined in claim 29 wherein said alterant elements are made reactive by the glow discharge.

31. The method as defined in claim 29 wherein said alterant elements comprise at least hydrogen and fluorine.

32. The method as defined in claim 29 wherein the plurality of compounds comprise silicon tetrafluoride and silane and the alterant elements separately contained in the atmosphere comprise at least hydrogen or fluorine.

33. The method as defined in claim 29 wherein the atmosphere for the glow discharge decomposition separately contains a modifier element which is incorporated in said amorphous semiconductor host matrix during the formation thereof yielding a modified amorphous semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

34. The method as defined in claim 33 wherein said modifier element is made reactive by the glow discharge.

35. The method of making a semiconductor film comprising a solid amorphous alloy semiconductor host matrix including a plurality of elements and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous alloy semiconductor host matrix including a plurality of elements by glow discharge decomposition of a plurality of compounds, each containing at least one of said elements and at least one alterant element, in a partial vacuum having an atmosphere separately containing at least one different alterant element and not derived from the compounds, wherein said different at least one alterant elements of said compounds and separately contained in said atmosphere comprise at least fluorine and are incorporated in said amorphous alloy semiconductor host matrix during deposition thereof yielding an altered amorphous alloy semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

36. The method as defined in claim 35 wherein said alterant elements are made reactive by the glow discharge.

37. The method as defined in claim 35 wherein said alterant elements comprise at least hydrogen.

38. The method as defined in claim 35 wherein the amorphous alloy semiconductor material includes elements from Groups III, IV, V and VI of the periodic table.

39. The method as defined in claim 35 wherein the amorphous alloy semiconductor material includes boron, carbon or nitrogen to withstand high temperatures.

40. The method as defined in claim 35 wherein the atmosphere for the glow discharge decomposition separately contains a modifier element which is incorporated in said amorphous alloy semiconductor host matrix during the formation thereof yielding a modified amorphous alloy semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap, such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

41. The method as defined in claim 40 wherein said modifier material is made reactive by the glow discharge.

42. The method of producing an amorphous semiconductor film comprising a solid amorphous semiconductor host matrix with electronic configurations which have an energy gap and a low density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix by glow discharge decomposition of at least one compound and incorporating in said amorphous semiconductor host matrix during deposition thereof a plurality of different complementary alterant elements, including at least fluorine, yielding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

43. The method as defined in claim 42 wherein the reduced density of localized states occur near the center of the energy gap and in the upper half and/or the lower half of the energy gap.

44. The method as defined in claim 42 wherein said alterant elements are made reactive by the glow discharge.

45. The method as defined in claim 42 wherein said compensating elements comprise at least hydrogen.

46. The method as defined in claim 42 comprising incorporating in said amorphous semiconductor host matrix during deposition thereof a modifier element yielding a modified amorphous semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap.

47. The method as defined in claim 43 comprising incorporating in said amorphous semiconductor host matrix during deposition thereof a modifier element yielding a modified amorphous semiconductor material having modified electronic configuration with the introduction of localized states in the energy gap, such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

48. The method as defined in claim 46 wherein said modifier element is made reactive by the glow discharge.

49. The method of making a semiconductor film comprising a solid amorphous semiconductor host matrix including at least one element and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix including at least one element by glow discharge decomposition of a compound containing said at least one element and at least one alterant element comprising fluorine in a partial vacuum having an atmosphere separately containing at least one alterant element different from said at least one alterant element of the compound, wherein said at least one different alterant element separately contained in the atmosphere facilitates the glow discharge decomposition of said compound and deposition of said amorphous semiconductor host matrix, and wherein said at least one alterant element of said compound is incorporated in said amorphous semiconductor host matrix during deposition thereof yielding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.

50. The method as defined in claim 49 wherein said alterant elements are made reactive by the glow discharge.

51. The method as defined in claim 49 wherein said at least one element of the amorphous semiconductor host matrix includes silicon.

52. The method as defined in claim 49 wherein said compound includes silicon and fluorine and said atmosphere includes hydrogen.

53. The method as defined in claim 52 wherein said compound comprises silicon tetrafluoride.

55. The method as defined in claim 49 wherein the atmosphere for the glow discharge decomposition separately contains a modifier element which is incorporated in said amorphous semiconductor host matrix in parts per million during formation thereof yielding a modified amorphous semiconductor material having modified electronic configurations with the introduction of localized states in the energy gap.

56. The method as defined in claim 55 wherein the modified amorphous semiconductor material is such that the Fermi level is moved to the vicinity of either the valence band or the conduction band.

57. The method as defined in claim 55 wherein said modifier element is made reactive by the glow discharge.

54. The method of making a semiconductor film comprising a solid amorphous semiconductor host matrix including silicon and having electronic configurations which have an energy gap and a density of localized states therein, said method comprising depositing on a substrate a solid amorphous semiconductor host matrix including silicon by glow discharge decomposition of a compound containing silicon and an alterant element including fluorine, wherein said alterant element of said compound is incorporated in said amorphous semiconductor host matrix during deposition thereof yielding an altered amorphous semiconductor material having altered electronic configurations with a reduced density of localized states in the energy gap.