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US 6,674,091 B2Granted
Multi-quantum-well detector for low-background applications
AssigneeCalifornia Institute of Technology
InventorsSarath D. Gunapala, Sumith V. Bandara, John K. Liu, Sir B. Rafol, David Z. Ting, Jason M. Mumolo
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Abstract
Device designs and techniques for reducing the dark current in quantum-well detectors.
Claims11
A device, comprising a radiation detector which includes:
- an emitter contact layer;
- a multi-quantum-well structure having a first side in contact with said emitter contact layer and an opposing second side, said multi-quantum-well structure formed of alternating quantum well layers and barrier layers, each barrier layer being of a thickness that allows for a spatial overlap of wavefunctions of adjacent quantum wells to form a common miniband within the quantum wells and to permit a tunneling therethrough from one quantum well to an adjacent quantum well;
- a blocking barrier layer in contact with said second side of said multi-quantum-well structure and having a thickness that substantially prohibits a tunneling therethrough;
- a collector contact layer in contact with said blocking barrier layer;
- a cryogenic chamber that encloses said radiation detector and maintains a chamber temperature between 20 K and 50 K during operation of said radiation detector;
- and
- a CMOS readout circuit coupled to said collector contact layer to receive a signal caused by radiation absorbed by said multi-quantum-well structure.
4 more elements
A method, comprising:
- providing a multi-quantum-well structure to allow for carrier tunneling through a barrier layer from one quantum well to an adjacent quantum well to provide carriers for optical absorption, wherein the multi-quantum-well structure includes quantum wells separated by thick barrier layers to spatially overlap wavefunctions of the quantum wells to form a first common miniband within the quantum wells and a second common miniband as a quasibound state at a top of the quantum wells;
- and
- preventing any carrier tunneling from the multi-quantum-well structure to a contact layer that receives carriers from the multi-quantum-well structure to reduce a dark current.
A device, comprising:
- a first contact layer formed of a conductive material;
- a multi-quantum-well structure having a first side in contact with said first contact layer and an opposing second side, said multi-quantum-well structure formed of alternating quantum well and barrier layers, each barrier layer being sufficiently thin to spatially overlap wavefunctions of quantum wells to form a first common miniband within said quantum wells, said multi-quantum-well structure configured to have a second common quasibound miniband at a top of said quantum wells to allow for an intraband transition between said first common miniband and said second common qusibound miniband;
- a blocking barrier layer in contact with said second side of said multi-quantum-well structure and having a thickness that substantially prohibits a tunneling therethrough;
- and
- a second contact layer formed of a conductive material and in contact with said blocking barrier layer, wherein said first and said second contact layer are electrically coupled to supply a driving voltage to said multi-quantum-well structure.
2 more elements
Dependencies are inferred from the claim text.