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US 6,184,538 B2Granted
Dual-band quantum-well infrared sensing array having commonly biased contact layers
AssigneeCalifornia Institute of Technology
InventorsSumith V. Bandara, Sarath D. Gunapala, John K. Liu
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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.
Claims20
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.
3 more elements
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 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.
6 more elements
A method for constructing and using a semiconductor radiation sensing array to detect radiation having at least two wavelengths, comprising:
- 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.
Dependencies are inferred from the claim text.