Claims
- 1. A method for reducing leakage current and improving spectral resolution in CdZnTe crystals, comprising the steps of:
a) etching the surface of a CdZnTe crystal with a solution of bromine in methanol; b) applying electrodes onto the etched surface of the CdZnTe crystal; and c) passivating CdZnTe crystal by growing a dielectric layer on said etched surface so as to form a coherent, continuous layer consisting essentially of CdO.
- 2. The method of claim 1, wherein the step of etching comprises etching in a solution 5 v/o bromine in methanol.
- 3. The method of claim 1, wherein said step of passivating comprises treating the surface of the CdZnTe crystal with a solution of ammonium fluorine and hydrogen peroxide in water.
- 4. The method of claim 3, wherein the ammonium fluoride is replaced by an ammonium halide salt.
- 5. The method in claim 4, wherein the ammonium salts include NH4F, NH4Cl, NH4Br, NH4I.
- 6. The method of claim 3, wherein the CdZnTe crystal is treated with the ammonium fluoride and hydrogen peroxide solution for at least about 10 minutes.
- 7. The method of claim 3, wherein both ammonium fluoride and hydrogen peroxide are each present in an amount equal to about 10 w/o of an aqueous solution.
- 8. The method claim 1, wherein the CdZnTe crystal is replaced by any semiconductor compound consisting essentially of the group of elements listed in Groups 2B through 6B of the Periodic Tables of Elements.
- 9. The method in claim 3, wherein the hydrogen peroxide is replaced with an oxidizing agent having a Standard Reduction Half Cell Electrode potential that has a more positive potential than the hydrogen peroxide.
- 10. The method of claim 1, wherein the step of applying electrodes comprises depositing electrodes by thermal evaporation.
- 11. The method of claim 1, wherein the step of applying electrodes comprises depositing electrodes by plasma sputtering method.
- 12. The method of claim 1, wherein the step of applying electrodes comprises depositing electroless gold electrodes.
- 13. The method of claim 1, wherein the CdZnTe crystal has the composition of Cd1−xZnxTe, and where x is less than or equal to 0.5.
- 14. The method of claim 13, wherein the CdZnTe crystal has the composition Cd0.9Zn0.1Te.
- 15. The method of claim 1, wherein the step of passivating includes the step of encapsulating said CdZnTe crystal to provide a barrier between said dielectric layer and gases present in ambient air.
- 16. The method of claim 15, wherein said step of encapsulating includes forming a polymer layer on said dielectric layer.
- 17. The method of claim 16, wherein said polymer layer comprises HumiSeal® type 1B12.
- 18. The method of claim 15, wherein said step of encapsulating includes depositing a reactively sputtered hard-coat nitride layer on said dielectric layer.
- 19. The method of claim 18, wherein the hard-coat nitride layer is selected from the group consisting essentially of silicon nitride, boron nitride, germanium nitride, aluminum nitride, or gallium nitride.
- 20. A method for forming a detector sensitive to ionizing radiation, comprising the steps of:
a) etching the surface of a CdZnTe crystal with a solution of bromine in methanol; b) passivating the CdZnTe crystal by growing a dielectric layer on said etched surface forming thereby a passivated surface; c) applying a photoresist layer onto said dielectric layer; d) exposing a portion of said photoresist using electromagnetic radiation and a lithography means; e) developing and removing said exposed portion thereby creating an image pattern in said photoresist and exposing a corresponding portion of said passivated surface; f) removing said corresponding portion and thereby replicating said image onto said CdZnTe crystal surface; g) depositing a metal conductor onto said surface image thereby forming an electrode on said exposed CdZnTe crystal surface; and h) removing the remaining photoresist layer.
- 21. The method of claim 20, wherein the step of etching comprises etching in a solution 5 v/o bromine in methanol.
- 22. The method of claim 20, wherein said step of growing a dielectric layer comprises treating the surface of the CdZnTe crystal with a solution of about 10 w/o ammonium fluoride and about 10 w/o hydrogen peroxide in water.
- 23. The method of claim 20, wherein said lithography means comprises radiation from wavelengths of about 1 nm to about 750 nm.
- 24. The method of claim 20, wherein said lithography means comprises either a positive or a negative mask, said mask used in one of either a contact, a projection, or a reflection mode.
- 25. The method of claim 20, wherein the step of etching includes utilizing an acid, ion, plasma, or reactive ion plasma etching.
- 26. The method of claim 22, wherein both ammonium fluoride and hydrogen peroxide in equal amounts are 20 w/o of an aqueous solution.
- 27. The method of claim 26, wherein the electrodes are selected from the group of elements on the Periodic Table of elements in groups 8A through 1B.
- 28. The method of claim 27, wherein the metal is gold.
- 29. The method of claim 20, wherein the CdZnTe crystal has the composition of Cd1−xZnxTe, and where x is less than or equal to 0.5.
- 30. The method of claim 29, wherein the CdZnTe crystal has the composition Cd0.9Zn0.1Te.
- 31. The method of claim 20, wherein the step of passivating includes the step of encapsulating said CdZnTe crystal to provide a barrier between said dielectric layer and gases present in ambient air.
- 32. The method of claim 31, wherein said step of encapsulating includes forming a polymer layer on said dielectric layer.
- 33. The method of claim 32, wherein said polymer layer comprises HumiSeal® type 1B12.
- 34. The method of claim 31, wherein said step of encapsulating includes depositing a reactively sputtered hard-coat nitride layer on said dielectric layer.
- 35. The method of claim 34, wherein the hard-coat nitride layer is selected from the group consisting essentially of silicon nitride, boron nitride, germanium nitride, aluminum nitride, or gallium nitride.
- 36. A method for forming a detector sensitive to ionizing radiation, comprising the steps of:
a) etching the surface of a CdZnTe crystal with a solution of bromine in methanol; b) applying a photoresist layer onto said etched surface; c) exposing a portion of said photoresist using an electromagnetic radiation and a lithography means; d) developing and removing said exposed photoresist thereby leaving a portion of said surface uncovered; e) passivating said uncovered surface portion by growing a dielectric layer on said surface portion; f) removing said photoresist layer to create a pattern image in said dielectric layer and exposing a corresponding portion of said CZT crystal surface; and g) depositing a metal conductor onto said exposed surface thereby forming an electrode on said CdZnTe crystal surface.
- 37. The method of claim 36, wherein the step of etching comprises etching in a solution 5 v/o bromine in methanol.
- 38. The method of claim 36, wherein said step of growing a dielectric layer comprises treating the surface of the CdZnTe crystal with a solution of ammonium fluoride and hydrogen peroxide in water.
- 39. The method of claim 36, wherein said lithographic means further comprises radiation from wavelengths of about 1 nm to about 750 nm.
- 40. The method of claim 36, wherein said lithographic means further comprises a positive or a negative mask, said mask used in either a contact, a projection, or a reflection mode.
- 41. The method of claim 36, wherein the step of etching includes utilizing an acid, ion, plasma, or reactive ion plasma etching.
- 42. The method of claim 38, wherein both ammonium fluoride and hydrogen peroxide in equal amounts are 20 w/o of an aqueous solution.
- 43. The method of claim 42, wherein the electrodes are selected from the group of elements on the Periodic Table of elements in groups 8A through 1B.
- 44. The method of claim 43, wherein the metal is gold.
- 45. The method of claim 36, wherein the CdZnTe crystal has the composition of Cd1−xZnxTe, and where x is less than or equal to 0.5.
- 46. The method of claim 45, wherein the CdZnTe crystal has the composition Cd0.9Zn0.1Te.
- 47. The method of claim 36, wherein the step of passivating includes the step of encapsulating said CdZnTe crystal to provide a barrier between said dielectric layer and gases present in ambient air.
- 48. The method of claim 47, wherein said step of encapsulating includes forming a polymer layer on said dielectric layer.
- 49. The method of claim 48, wherein said polymer layer comprises HumiSeal® type 1B12.
- 50. The method of claim 47, wherein said step of encapsulating includes depositing a reactively sputtered hard-coat nitride layer on said dielectric layer.
- 51. The method of claim 50, wherein the hard-coat nitride layer is selected from the group consisting essentially of silicon nitride, boron nitride, germanium nitride, aluminum nitride, or gallium nitride.
- 52. A method for forming a detector sensitive to ionizing radiation, comprising the steps of:
a) etching the surface of a CdZnTe crystal with a solution of bromine in methanol; b) applying a photoresist layer onto said etched surface; c) exposing said photoresist using a lithographic means to create an exposed image of an electrode contact pattern in said photoresist; d) developing and removing said exposed photoresist to create a pattern image in said photoresist; e) depositing a metal conductor into said pattern and onto said etched surface; f) removing the remaining photoresist; and g) passivating the etch CdZnTe crystal surface by growing a dielectric layer on said uncovered surface.
- 53. The method of claim 52, wherein the step of etching comprises etching in a solution 5 v/o bromine in methanol.
- 54. The method of claim 52, wherein said step of growing a dielectric layer comprises treating the surface of the CdZnTe crystal with a solution of ammonium fluoride and hydrogen peroxide in water.
- 55. The method of claim 52, wherein said lithographic means further comprises radiation from wavelengths of about 1 nm to about 750 nm.
- 56. The method of claim 52, wherein said lithographic means further comprises a positive or a negative mask, said mask used in either a contact, a projection, or a reflection mode.
- 57. The method of claim 52, wherein the step of etching includes utilizing an acid, ion, plasma, or reactive ion plasma etching.
- 58. The method of claim 54, wherein both ammonium fluoride and hydrogen peroxide in equal amounts are 20 w/o of an aqueous solution.
- 59. The method of claim 52, wherein the electrodes are selected from the group of elements on the Periodic Table of elements in groups 8A through 1B.
- 60. The method of claim 59, wherein the metal is gold.
- 61. The method of claim 52, wherein the CdZnTe crystal has the composition of Cd1−xZnxTe, and where x is less than or equal to 0.5.
- 62. The method of claim 61, wherein the CdZnTe crystal has the composition Cd0.0Zn0.1Te.
- 63. The method of claim 52, wherein the step of passivating includes the step of encapsulating said CdZnTe crystal to provide a barrier between said dielectric layer and gases present in ambient air.
- 64. The method of claim 63, wherein said step of encapsulating includes forming a polymer layer on said dielectric layer.
- 65. The method of claim 64, wherein said polymer layer comprises HumiSeal® type 1B12.
- 66. The method of claim 63, wherein said step of encapsulating includes depositing a reactively sputtered hard-coat nitride layer on said dielectric layer.
- 67. The method of claim 66, wherein the hard-coat nitride layer is selected from the group consisting essentially of silicon nitride, boron nitride, germanium nitride, aluminum nitride, or gallium nitride.
- 68. An ionizing radiation detector, comprising:
a CdZnTe crystal having one or more surfaces; and a passivating dielectric layer grown on said surfaces, said layer consisting essentially of CdO.
- 69. The detector of claim 68, wherein the passivating layer is about at least 250 Å thick.
- 70. The detector of claim 68, further including an insulating means for providing a barrier between said dielectric layer and gases present in ambient air.
- 71. The detector of claim 70, wherein said insulating means includes a polymer layer on said dielectric layer.
- 72. The detector of claim 71, wherein said polymer layer comprises HumiSeal® type 1B12.
- 73. The detector of claim 70, wherein said insulating means includes a reactively sputtered hard-coat nitride layer deposited on said dielectric layer.
- 74. The detector of claim 73, wherein the hard-coat nitride layer is selected from the group consisting essentially of silicon nitride, boron nitride, germanium nitride, aluminum nitride, or gallium nitride.
- 75. The detector of claim 68, wherein the presence of the passivating dielectric layer reduces an initial measurement of surface current leakage by at least two orders of magnitude.
STATEMENT OF GOVERNMENT INTEREST
[0001] This invention was made with Government support under contract no. DE-AC04-94AL85000 awarded by the U. S. Department of Energy to Sandia Corporation. The Government has certain rights in the invention.
Divisions (1)
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Number |
Date |
Country |
Parent |
09536883 |
Mar 2000 |
US |
Child |
10325995 |
Dec 2002 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09118691 |
Jul 1998 |
US |
Child |
09536883 |
Mar 2000 |
US |