Heightened Performance for Infrared Imaging Detectors

Technology #31098

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A schematic drawing of a system for temperature coefficient of resistance (TCR) measurement used in the technology
Researchers
Kevin Coffey, Ph.D.
Vu Lam
Edward Dein
Andrew Warren, Ph.D.
Glenn Boreman, Ph.D.
Guy Zummo
Wilson Caba, Ph.D.
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Andrea Adkins
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Patent Protection

Nanocomposite semiconducting material with reduced resistivity

US Patent 8,502,639 B1

Nanocomposite semiconducting material with reduced resistivity

US Patent 8,228,159 B1

Nanocomposite Seminconducting Material with Reduced Resistivity

UCF researchers have developed a process for fabricating a nanocomposite semiconducting material with improved electrical properties. In microbolometers, this material and fabricating method increases response to temperature while reducing the material’s resistivity. Formed by simultaneously depositing an amorphous oxide and a noble metal, this thin film enhances the sensitivity of devices while improving power economy. In the past, infrared imaging and detection were mainly of interest for photon detectors used in military applications, which have excellent performance but are very expensive and must be cooled at cryogenic temperature. With today's heightened interest in security and surveillance, the civilian sector requires infrared detection and imaging. Microbolometers have become the instrument of choice, because they provide good performance at low-cost without difficult cooling requirements.

Technical Details

In imaging arrays and thermal cameras, microbolometers detect infrared radiation by responding to subtle changes to specific wavelengths. Infrared radiation is absorbed through the microbolometer that changes the electrical resistance of the thin film material inside. This material must have a high change in resistivity versus temperature, referred to as Temperature Coefficient of Resistance (TCR), as well as very low natural resistivity. Both parameters determine the performance and sensitivity of microbolometer thin films used in infrared imaging.

This invention reduces material resistivity by the inclusion of metals such as gold and platinum in the fabrication of the amorphous vanadium oxide (VOx) thin film. The inclusion of gold, which forms nanoclusters, also improves the TCR of the material. Including gold in the sputtering deposition process led to an improvement in the TCR of ~0.0075 1/°C. Further improvement in the ratio of TCR to resistivity is achieved by reduction of oxygen in the film. Compared to current models, this innovation reduces resistivity in the VOx material by nearly an order of magnitude while maintaining deposition stability through the reduction of oxygen from 3 to 0.5 percent.

Benefits

  • Sensitive in infrared imaging devices
  • Greater power economy of microbolometers
  • High TCR value

Applications

  • Thermal imaging
  • Imaging arrays
  • Conventional resistors
  • Electronic sensor applications

Additional Technology Numbers: 32484