Integrated IR, visible and NIR sensor and methods of fabricating same
First Claim
1. An imaging device having a plurality of unit cells that contribute to forming an image of a scene, said imaging device comprising a layer of wide bandgap semiconductor material having photogate charge-mode readout circuitry disposed upon a first surface of said layer, a second, opposing surface of said layer being bonded at a heterojunction interface to a surface of a layer of narrower bandgap semiconductor material selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer and for generating charge carriers, the generated charge carriers being transported across said heterojunction interface for collection by said photogate charge-mode readout circuitry, and further comprising a thermal sensing element disposed above and thermally isolated from said first surface of said layer.
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Accused Products
Abstract
An imaging device (10) has a plurality of unit cells that contribute to forming an image of a scene. The imaging device includes a layer of semiconductor material (16), for example silicon, that has low noise photogate charge-mode readout circuitry (20, 21, 26, 28) (e.g., CCD or CMOS readout circuitry and structures) that is disposed upon a first surface (18) of the layer. A second, opposing surface of the layer is a radiation admitting surface of the layer. The layer has a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers from the absorbed radiation. The generated charge carriers are collected by the photogate charge-mode readout circuitry. A thermal sensing element (22) is disposed above and is thermally isolated from the first surface of the layer. The thermal sensing element may be, by example, one of a bolometer element, a pyroelectric element, or a thermopile element. A layer (12) of narrower bandgap semiconductor material can also be employed with this invention, wherein the layer of narrower bandgap semiconductor material (such as InGaAs or HgCdTe) is atomically bonded to the second surface along a heterojunction interface that is continuous or apertured across the second surface. The bonded layer is used to absorb NIR and visible light.
349 Citations
29 Claims
- 1. An imaging device having a plurality of unit cells that contribute to forming an image of a scene, said imaging device comprising a layer of wide bandgap semiconductor material having photogate charge-mode readout circuitry disposed upon a first surface of said layer, a second, opposing surface of said layer being bonded at a heterojunction interface to a surface of a layer of narrower bandgap semiconductor material selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer and for generating charge carriers, the generated charge carriers being transported across said heterojunction interface for collection by said photogate charge-mode readout circuitry, and further comprising a thermal sensing element disposed above and thermally isolated from said first surface of said layer.
- 15. An imaging device having a plurality of unit cells that contribute to forming an image of a scene, said imaging device comprising a layer of semiconductor material having photogate charge-mode readout circuitry disposed upon a first surface of said layer, a second, opposing surface of said layer being a radiation admitting surface of said layer, said layer having a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers, the generated charge carriers being collected by said photogate charge-mode readout circuitry, and further comprising a thermal sensing element disposed above and thermally isolated from said first surface of said layer.
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27. An imaging device having a plurality of unit cells that contribute to forming an image of a scene, said imaging device comprising a layer of wide bandgap semiconductor material having readout circuitry employing a photodiode for charge collection, said readout circuitry being disposed upon a first surface of said layer, a second, opposing surface of said layer being bonded at a heterojunction interface to a surface of a layer of narrower bandgap semiconductor material selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer and for generating charge carriers, the generated charge carriers being transported across said heterojunction interface for collection by said photodiode readout circuitry, and further comprising a thermal sensing element disposed above and thermally isolated from said first surface of said layer.
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28. An imaging device having a plurality of unit cells that contribute to forming an image of a scene, said imaging device comprising a layer of semiconductor material having readout circuitry employing a photodiode for charge collection, said readout circuitry being disposed upon a first surface of said layer, a second, opposing surface of said layer being a radiation admitting surface of said layer, said layer having a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers, the generated charge carriers being collected by said photodiode readout circuitry, and further comprising a thermal sensing element disposed above and thermally isolated from said first surface of said layer.
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29. A monolithic mid wave IR (MWIR) or long wave IR (LWIR)/visible/NIR sensor array, comprising:
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a substrate having an atomically bonded, narrower bandgap layer on a first, radiation-receiving surface; and a plurality of detector sites disposed on a second, opposite surface of said substrate, each of said sites comprising, readout circuitry; a MWIR or LWIR-responsive detector disposed over said second surface of said substrate; and a plurality of visible/NIR detectors corresponding to each detector site, said plurality of visible/NIR detectors being interposed between said MWIR or LWIR-responsive detector and said second surface.
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Specification