United States Patent
US Patent 6870207: III-V charge coupled device suitable for visible…
US 6870207 · granted 2005-03-22
Abstract
A photon detector is obtained by using the intersubband absorption mechanism in a modulation doped quantum well(s). The modulation doping creates a very high electric field in the well which enables absorption of input TE polarized light and also conducts the carriers emitted from the well into the modulation doped layer from where they may recombine with carriers from the gate contact. Carriers are resupplied to the well by the generation of electrons across the energy gap of the quantum well material. The absorption is enhanced by the use of a resonant cavity in which the quantum well(s) are placed. The absorption and emission from the well creates a deficiency of charge in the quantum well proportional to the intensity of the input photon signal. The quantity of charge in the quantum well of each detector is converted to an output voltage by transferring the charge to the gate of an output amplifier. The detectors are arranged in the form of a 2D array with an output amplifier associated with the entire array or a row of the array as in the known charge coupled devices, or a separate amplifier could be dedicated to each pixel as in the known architecture of the active pixel device. This detector has the unique advantage of near room temperature operation because the dark current is limited to the generation across the semiconductor bandgap and not the emission over the quantum well barrier. The detector also has the advantage that the readout circuitry is implemented monolithically by the HFETs formed in the GaAs substrate simultaneously, with the detecting elements.
| Patent Number | 6870207 |
|---|---|
| Title | III-V charge coupled device suitable for visible, near and far infra-red detection |
| Filed | 2000-04-24 |
| Granted | 2005-03-22 |
| Inventor(s) | Taylor; Geoff W |
| Assignee | The University of Connecticut |
| CPC Classification | H01L 27/146 |
| Number of Claims | 36 |
Abstract
A photon detector is obtained by using the intersubband absorption mechanism in a modulation doped quantum well(s). The modulation doping creates a very high electric field in the well which enables absorption of input TE polarized light and also conducts the carriers emitted from the well into the modulation doped layer from where they may recombine with carriers from the gate contact. Carriers are resupplied to the well by the generation of electrons across the energy gap of the quantum well material. The absorption is enhanced by the use of a resonant cavity in which the quantum well(s) are placed. The absorption and emission from the well creates a deficiency of charge in the quantum well proportional to the intensity of the input photon signal. The quantity of charge in the quantum well of each detector is converted to an output voltage by transferring the charge to the gate of an output amplifier. The detectors are arranged in the form of a 2D array with an output amplifier associated with the entire array or a row of the array as in the known charge coupled devices, or a separate amplifier could be dedicated to each pixel as in the known architecture of the active pixel device. This detector has the unique advantage of near room temperature operation because the dark current is limited to the generation across the semiconductor bandgap and not the emission over the quantum well barrier. The detector also has the advantage that the readout circuitry is implemented monolithically by the HFETs formed in the GaAs substrate simultaneously, with the detecting elements.
Claim 1
A semiconductor imaging device, comprising: a) a semiinsulating gallium arsenide (GaAs) substrate; b) a distributed Bragg reflector mirror epitaxially grown on saidsemiinsulating GaAs substrate; c) a first layer of P+ type GaAs deposited on said distributed Bragg reflector mirror for contacting a collector electrode; d) at least one layer of aluminum gallium arsenide (AlGaAs) disposed on said first layer of P+type GaAs; e) an epitaxial layer structure of at least one quantum well of InGaAs having GaAs layers on each either side; f) a first spacer layer of AlGaAs disposed on said epitaxial layer structure; g) an N type modulation doped layer of AlGaAsdisposed on said first spacer layer; h) a second spacer layer of AlGaAs disposed on said modulation doped layer; i) a planar doped layer of P+ type AlGaAs disposed on said second spacer layer; j) a cladding layer of AlGaAs of modest P type dopingdisposed on said planar doped layer; and k) a layer of GaAs of P++ type doping disposed on said cladding layer for contacting a gate electrode, wherein a forward bias is applied to said gate electrode with respect to said collector electrode such thatlight incident on said semiconductor imaging
Claims
36 totalA semiconductor imaging device, comprising: a) a semiinsulating gallium arsenide (GaAs) substrate; b) a distributed Bragg reflector mirror epitaxially grown on saidsemiinsulating GaAs substrate; c) a first layer of P+ type GaAs deposited on said distributed Bragg reflector mirror for contacting a collector electrode; d) at least one layer of aluminum gallium arsenide (AlGaAs) disposed on said first layer of P+type GaAs; e) an epitaxial layer structure of at least one quantum well of InGaAs having GaAs layers on each either side; f) a first spacer layer of AlGaAs disposed on said epitaxial layer structure; g) an N type modulation doped layer of AlGaAsdisposed on said first spacer layer; h) a second spacer layer of AlGaAs disposed on said modulation doped layer; i) a planar doped layer of P+ type AlGaAs disposed on said second spacer layer; j) a cladding layer of AlGaAs of modest P type dopingdisposed on said planar doped layer; and k) a layer of GaAs of P++ type doping disposed on said cladding layer for contacting a gate electrode, wherein a forward bias is applied to said gate electrode with respect to said collector electrode such thatlight incident on said semiconductor imaging