Photoconductive bolometer infrared detector
First Claim
1. A photoconductive microbolometer detector, comprising:
- a detector layer suspended over a substrate, wherein the detector layer has a resistance variable by photo excitation and thermal excitation caused by an incident long-, medium-or short-wavelength infrared radiation; and
a readout circuit formed in the substrate supplying a bias current to the detector layer, the readout circuit being operative to read resistance change of the detector layer caused by the incident infrared radiation impinging on the detector layer.
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Abstract
A photoconductive bolometer infrared detector using a detector material that has a resistance changed due to photo-excitation and thermal-excitation from an incident radiation in the infrared range. The resistance changes caused by photo-excitation and the thermal excitation are additive for this detector material. The detector material is suspended over a substrate by a gap of one quarter wavelength of the incident radiation, such that the thermal absorption of the incident radiation can be enhanced. Preferably, the detector material is lead selenide that has a thermal coefficient of resistance as high as 3.45%° C.−1, which is about 60% higher than that of vanadium oxide that has been widely used as the detector material in the conventional microbolometers. This detector structure allows dual band uncooled or moderately cooled operation. In the case of the use of PbSe as the detector material, largely enhanced MWIR operation is enabled over a standard uncooled micro-bolometer tuned to the LWIR, and high temperature dual band MWIR and LWIR operation is enabled as compared to quantum well or HgCdTe detectors that must be cooled to cryogenic temperatures.
15 Citations
31 Claims
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1. A photoconductive microbolometer detector, comprising:
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a detector layer suspended over a substrate, wherein the detector layer has a resistance variable by photo excitation and thermal excitation caused by an incident long-, medium-or short-wavelength infrared radiation; and a readout circuit formed in the substrate supplying a bias current to the detector layer, the readout circuit being operative to read resistance change of the detector layer caused by the incident infrared radiation impinging on the detector layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A photoconductive microbolometer detector, comprising:
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a lead selenide detector layer suspended over a substrate; at least two legs supporting the detector layer to suspend over the substrate; and a readout circuit in the substrate for supplying a bias current to the detector layer and to read resistance change of the detector layer when incident radiation impinges thereon. - View Dependent Claims (12, 13, 14)
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15. A photoconductive microbolometer detection device, comprising:
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a substrate; a plurality of photoconductive microbolometer detector units suspended over the substrate, each of the detector units includes a detector layer; and a readout circuit formed in the substrate for supplying a bias current to and to detect an electrical resistance change of each photoconductive microbolometer detector units is caused by both photo-excitation and thermal-excitation of each detector layer by an incident long-, medium-, or short-wavelength infrared radiation. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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- 26. A photoconductive microbolometer infrared detector, comprising a detector layer made of selenide, wherein the detector is operative to detect a long, medium-, or short wavelength infrared signal incident thereon by measuring an electric resistance change thereof.
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31. A photoconductive microbolometer infrared detector, comprising:
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a substrate; and a plurality of lead selenide layers suspended over the substrate.
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Specification