Dual-band quantum-well infrared sensing array having commonly biased contact layers
First Claim
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1. A semiconductor radiation sensing array comprising a plurality of sensing pixels formed on a semiconductor substrate, each sensing pixel including:
- a first semiconductor contact layer doped to have a predetermined type of conductivity;
a first quantum-well sensing stack formed over said first semiconductor contact layer and configured to have a plurality of alternating semiconductor layers which form a first number of quantum wells of a first well width and are doped at a first doping level, said first quantum-well sensing stack responsive to radiation at a first operating wavelength to produce a first amount of charged carriers;
at least one second semiconductor contact layer doped to have said predetermined type of conductivity and formed on said first quantum-well sensing stack;
a second quantum-well sensing stack formed over said second semiconductor contact layer and configured to have a plurality of alternating semiconductor layers which form a second number of quantum wells of a second well width and are doped at a second doping level, said second quantum-well sensing stack responsive to radiation at a second operating wavelength different than said first operating wavelength to produce a second amount of charged carriers;
a third semiconductor contact layer doped to have said predetermined type of conductivity and formed on said second quantum-well sensing stack, wherein said first and third semiconductor contact layers are maintained at a common bias electrical potential with respect to said second semiconductor contact layer so that said first and second quantum-well sensing stacks are biased by a common voltage difference.
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Abstract
Quantum-well sensing arrays for detecting radiation with two or more wavelengths. Each pixel includes at least two different quantum-well sensing stacks that are biased at a common voltage.
80 Citations
20 Claims
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1. A semiconductor radiation sensing array comprising a plurality of sensing pixels formed on a semiconductor substrate, each sensing pixel including:
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a first semiconductor contact layer doped to have a predetermined type of conductivity;
a first quantum-well sensing stack formed over said first semiconductor contact layer and configured to have a plurality of alternating semiconductor layers which form a first number of quantum wells of a first well width and are doped at a first doping level, said first quantum-well sensing stack responsive to radiation at a first operating wavelength to produce a first amount of charged carriers;
at least one second semiconductor contact layer doped to have said predetermined type of conductivity and formed on said first quantum-well sensing stack;
a second quantum-well sensing stack formed over said second semiconductor contact layer and configured to have a plurality of alternating semiconductor layers which form a second number of quantum wells of a second well width and are doped at a second doping level, said second quantum-well sensing stack responsive to radiation at a second operating wavelength different than said first operating wavelength to produce a second amount of charged carriers;
a third semiconductor contact layer doped to have said predetermined type of conductivity and formed on said second quantum-well sensing stack, wherein said first and third semiconductor contact layers are maintained at a common bias electrical potential with respect to said second semiconductor contact layer so that said first and second quantum-well sensing stacks are biased by a common voltage difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A semiconductor radiation sensing array comprising a plurality of sensing pixels formed on a semiconductor substrate, each sensing pixel including:
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a first semiconductor contact layer doped to have a predetermined type of conductivity;
a first quantum-well sensing stack formed over said first semiconductor contact layer and configured to have a plurality of quantum-wells formed of alternating semiconductor layers and responsive to radiation at a first operating wavelength to produce a first amount of charged carriers;
at least one second semiconductor contact layer doped to have said predetermined type of conductivity and formed on said first quantum-well sensing stack, said second semiconductor contact layer having a first portion and a second portion;
a second quantum-well sensing stack formed over said first portion of said second semiconductor contact layer and configured to have a plurality of quantum wells formed of alternating semiconductor layers and responsive to radiation at a second operating wavelength different than said first operating wavelength to produce a second amount of charged carriers;
a first radiation-reflective layer formed over said second portion of said second semiconductor contact layer;
a third semiconductor contact layer doped to have said predetermined type of conductivity and formed on said second quantum-well sensing stack; and
a second radiation-reflective layer formed over said third semiconductor contact layer, wherein said first and third semiconductor contact layers are maintained at a common bias electrical potential with respect to said second semiconductor contact layer so that said first and second quantum-well sensing stacks are biased by a common voltage difference. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for constructing and using a semiconductor radiation sensing array to detect radiation having at least two wavelengths, comprising:
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forming a first quantum-well sensing stack and a second quantum-well sensing stack in a sensing pixel to respectively detect radiation at a first operating wavelength and radiation at a second operating wavelength, wherein said first and second quantum-well sensing stacks have different number of quantum wells; and
applying a common bias electrical voltage to both said first and second quantum-well sensing stacks to produce first and second photocurrents that respectively represent intensities at said first and second operating wavelengths in the received radiation. - View Dependent Claims (19, 20)
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Specification