Low voltage low light imager and photodetector
First Claim
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1. A photodetector comprising:
- a photocathode formed of a non-cesiated, semiconductor material, said photocathode having an activation layer that has one of either a piezoelectrically induced polarization field or a delta-doped surface, such that where at least one photon within a selected wavelength range impinges on said photocathode at least one electron is emitted from the surface of said photocathode;
a thinned delta-doped imager array, said imager array being disposed across an accelerating gap from said photocathode;
an electric field generator for generating an electric field across said accelerating gap, said electrical field generator being disposed in relation to said imager array and said photocathode such that the electric field accelerates said at least one electron across said accelerating gap to impinge on said imager array; and
wherein the accelerating gap is sufficiently small such that the electrons produced from said photocathode are proximity focused onto said imager array such that a plurality of electrons are generated from each of the accelerated electrons that impinge thereon, and wherein only a single electron is generated for photons that impinge directly thereon.
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Abstract
Highly efficient, low energy, low light level imagers and photodetectors are provided. In particular, a novel class of Della-Doped Electron Bombarded Array (DDEBA) photodetectors that will reduce the size, mass, power, complexity, and cost of conventional imaging systems while improving performance by using a thinned imager that is capable of detecting low-energy electrons, has high gain, and is of low noise.
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Citations
36 Claims
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1. A photodetector comprising:
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a photocathode formed of a non-cesiated, semiconductor material, said photocathode having an activation layer that has one of either a piezoelectrically induced polarization field or a delta-doped surface, such that where at least one photon within a selected wavelength range impinges on said photocathode at least one electron is emitted from the surface of said photocathode; a thinned delta-doped imager array, said imager array being disposed across an accelerating gap from said photocathode; an electric field generator for generating an electric field across said accelerating gap, said electrical field generator being disposed in relation to said imager array and said photocathode such that the electric field accelerates said at least one electron across said accelerating gap to impinge on said imager array; and wherein the accelerating gap is sufficiently small such that the electrons produced from said photocathode are proximity focused onto said imager array such that a plurality of electrons are generated from each of the accelerated electrons that impinge thereon, and wherein only a single electron is generated for photons that impinge directly thereon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A photodetector comprising:
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a photocathode formed of a non-cesiated, semiconductor material, said photocathode having an activation layer that has one of either a piezoelectrically induced polarization field or a delta-doped surface, such that where at least one photon within a selected wavelength range impinges on said photocathode at least one electron is emitted from the surface of said photocathode; a thinned delta-doped imager array, said imager array being disposed across an accelerating gap from said photocathode; an electric field generator for generating an electric field across said accelerating gap, said electrical field generator being disposed in relation to said imager array and said photocathode such that the electric field accelerates said at least one electron across said accelerating gap to impinge on said imager array; wherein the accelerating gap is sufficiently small such that the electrons produced from said photocathode are proximity focused onto said imager array such that a plurality of electrons are generated from each of the accelerated electrons that impinge thereon, and wherein only a single electron is generated for photons that impinge directly thereon; and detector circuitry in signal communication with said imager array for monitoring said signal and applying a threshold detection level to said signal to filter noise from said signal.
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20. A method of forming a photodetector comprising:
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providing at least one spacer having first and second ends; disposing at one end of said spacer a photocathode formed of a non-cesiated, semiconductor material having an activation layer that has one of either a piezoelectrically induced polarization field or a delta-doped surface, wherein said activation layer enables at least one photon within a wavelength range that impinges on said photocathode to cause emission of at least one electron from the surface of said photocathode; disposing at the other end of said spacer a thinned delta-doped imager array; and wherein the space between said photocathode and said imager array defines an accelerating gap, wherein the accelerating gap is sufficiently small such that the electrons from said photocathode are proximity focused onto said imager array; disposing an electric field generator into electrical communication with said accelerating gap, such that said electric field generator generates an electric field across said accelerating gap, said electric field being designed to accelerate said at least one electron from said photocathode across said accelerating gap; and wherein the imager array creates a signal by producing a plurality of electrons from each of the accelerated electrons that impinges thereon, while generating only a single electron for photons that impinge directly thereon. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification