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Direct Detector for Terahertz Radiation

Sandia National Laboratories

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PDF Document PublicationMarket Sheet (893 KB)


Technology Marketing SummaryThere has been much interest expressed in terahertz technology due to the diverse range of applications that it applies to.  However, the terahertz components have been known to perform poorly due to it lying between traditional electronic and photonic fields.  Sandia National Laboratories has created a direct detector for terahertz radiation that seeks to close the "technological gap".DescriptionThe present invention is a direct detector that is a depletion mode field effect transistor built from heterostructures and consisting of electrical contacts and a grating-gate.  The grating gate tunes the electron density of the detector and adjusts the Plasmon frequency to match the THz radiation illuminating the device.  The detector shows a photoresponse when the Plasmon frequency under the grating gate was turned to the frequency of the incident illumination, a capability not found in other terahertz devices. Benefits
  • Plasmons are not tied to the bandgap energy and can be excited by small THz photon energies
  • Plasmons can be excited at high temperatures than the THz photon energy
  • Detector is easier to produce and control
  • Easier to integrate with additional electronics
  • Requires lower voltage
Applications and Industries
  • National Defense and Security
  • Molecular Spectroscopy
  • Imaging Array
  • Medical Imaging
  • Remote Sensing
  • Electronics
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 7,420,225
Patent
7,420,225
Direct detector for terahertz radiation
A direct detector for terahertz radiation comprises a grating-gated field-effect transistor with one or more quantum wells that provide a two-dimensional electron gas in the channel region. The grating gate can be a split-grating gate having at least one finger that can be individually biased. Biasing an individual finger of the split-grating gate to near pinch-off greatly increases the detector's resonant response magnitude over prior QW FET detectors while maintaining frequency selectivity. The split-grating-gated QW FET shows a tunable resonant plasmon response to FIR radiation that makes possible an electrically sweepable spectrometer-on-a-chip with no moving mechanical optical parts. Further, the narrow spectral response and signal-to-noise are adequate for use of the split-grating-gated QW FET in a passive, multispectral terahertz imaging system. The detector can be operated in a photoconductive or a photovoltaic mode. Other embodiments include uniform front and back gates to independently vary the carrier densities in the channel region, a thinned substrate to increase bolometric responsivity, and a resistive shunt to connect the fingers of the grating gate in parallel and provide a uniform gate-channel voltage along the length of the channel to increase the responsivity and improve the spectral resolution.
Sandia National Laboratories 09/02/2008
Issued
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
US Patent# 7,420,225Prototype - Sandia estimates this technology at approximately TRL 5. Key elements have been demonstrated in relevant environments. Available - Various licensing and partnering options are available. Please contact the Intellectual Property Department to discuss.09/28/201103/19/2013

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To: Technology Inquiries<ip@sandia.gov>