Microdischarge Photodetectors

 

This invention allows for the production of a family of photodetectors that are sensitive in the ultraviolet, visible, and near-infrared regions of the spectrum. Despite previous knowledge of photo responses to low pressure gas discharges, this technology is the first to achieve these responses without using plasma as the photosensitive element. The plasma instead amplifies the number of photoelectrons produced by the cathode's avalanche effect. Furthermore, the electronic properties of the photocathode material determine the spectral response of the photodetector. These photocathodes can then be composed of different materials to optimize the photodetector for more specific responsiveness.

Details

As the spatial dimensions of microplasma devices have continued to decrease they have become attractive for an increasingly wide range of applications. The microdischarge devices this technology enables are sensitive detectors of visible, near-IR, and UV radiation and significantly extend the use of silicon devices. The wavelength range over which microdischarge detectors are photosensitive can be extended by simply changing the photocathode material Therefore, detectors have a significant advantage over their semiconductor counterparts because of the wavelength agility available with a single, rugged device structure. Furthermore, the crystalline quality of the semiconductor photocathode in the microplasma device is unlikely to be critical. Consequently, one has the option of micromachining the detector from silicon and overcoating the cathode with a film of the appropriate semiconductor (or other material). Since this detector is fabricated in silicon, large arrays of devices can be produced economically. To date, arrays as large as 250,000 (500 x 500) have been tested successfully. These photodetectors combined with other advances in microdischarge technology lead to a bright future for nearly any application involving light. Information about other devices and applications using UIUC Microdischarge technology is available on request.

Benefits

  • Amenable to mass production: This invention can be readily integrated with other electronic or optoelectronic devices.
  • Inexpensive: Because this device does not depend on the existence of a p-n junction the crystalline quality of the semiconductor is not an issue.
  • More sensitive: This invention provides a photodetector in the visible and UV that is considerably more sensitive than commercial Si photodiodes.