Innovation and Partnerships Office

More Sensitive, Less Expensive Semiconductor Detectors IB-2607

APPLICATIONS OF TECHNOLOGY:

Radiation detection for

  • Defense and homeland security
  • Medical imaging: CT, PET, and SPECT
  • Nuclear power monitoring
  • Industrial gauging, e.g., tank fill level, materials thickness sensing
  • Research involving spectrometry and imaging

ADVANTAGES:

  • Finer position resolution that current technology
  • More accurate measurement by bulk detectors
  • Eliminates hard-wired connections for signal readout
  • Enables simpler, less expensive fabrication from diverse materials
  • Can be fabricated with less thermal and mechanical stress to materials

ABSTRACT:

Paul Luke and colleagues from Berkeley Lab have invented a semiconductor detector that can be easily fabricated at a lower cost and from more diverse materials than conventional semiconductor detectors while providing better position and energy resolution. The technology uses readout electrodes in close proximity to, rather than in direct contact with, the semiconductor. This eliminates the need for multiple electrical connections between detectors and readout electronics. Furthermore, the device can interpolate the signals at different “proximity” electrodes, thereby providing more precise position resolution with fewer electrodes than needed in existing devices.

Until now, semiconductor detectors had readout electrodes on the surface of the semiconductor. These electrodes must be finely segmented and each segment separately connected to an amplifier to provide precise position information. Multiple connections are fabricated by complex, expensive techniques that cannot be applied to many semiconductor and readout materials because the materials cannot withstand the mechanical and thermal stress of fabrication. The Berkeley Lab invention overcomes these limitations by using non-contact proximity electrodes in which a charge is induced and measured. Thus, the device circumvents the need for multiple connections to the surface of the semiconductor.

In an alternative construction, the proximity electrodes can be used to improve the precision and reduce spectral background in large-volume detectors, such as those of Ge, CdZnTe, and Si (Li) used in gamma ray and x-ray spectroscopy. Charge carriers in such detectors often collect along the side surfaces, resulting in incomplete charge collection at the detector contact and leading to inaccurately reduced signal amplitude. The Berkeley Lab proximity electrodes can be used to sense charge carriers along the side surfaces and indicate that an event has been inaccurately measured at the detector contact.

STATUS:

  • Published Patent Application 12/604,173 available at www.uspto.gov. Available for licensing or collaborative research.

DEVELOPMENT STAGE:

  • Proof of principle.

To learn more about licensing a technology from LBNL see here.

FOR MORE INFORMATION:

Luke P.N., C.S. Tindall, M. Amman. “Proximity charge sensing with semiconductor detectors,” IEEE Trans Nucl Sci. 56(3):808-812 (2009).

REFERENCE NUMBER: IB-2607

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