Study of gain phenomenon in lateral metal-semiconductor-metal detectors for indirect conversion medical imaging

Shiva Abbaszadeh, Nicholas Allec, Kai Wang, Feng Chen, Karim S. Karim

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Previously, metal-semiconductor-metal (MSM) lateral amorphous selenium (a-Se) detectors have been proposed for indirect detector medical imaging applications. These detectors have raised interest due to their high-speed and photogain. The gain measured from these devices was assumed to have been photoconductive gain; however the origin of this gain was not fully understood. In addition, whether or not there was any presence of photocurrent multiplication gain was not investigated. For integration-type applications photocurrent multiplication gain is desirable since the total collected charge can be greater than the total number of absorbed photons. In order to fully appreciate the value of MSM devices and their benefit for different applications, whether it is counting or integration applications, we need to investigate the responsible mechanisms of the observed response. In this paper, we systematically study, through experimental and theoretical means, the nature of the photoresponse and its responsible mechanisms. This study also exposes the possible means to increase the performance of the device and under what conditions it will be most beneficial.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2011
Subtitle of host publicationPhysics of Medical Imaging
StatePublished - May 13 2011
EventMedical Imaging 2011: Physics of Medical Imaging - Lake Buena Vista, FL, United States
Duration: Feb 13 2011Feb 17 2011

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherMedical Imaging 2011: Physics of Medical Imaging
CountryUnited States
CityLake Buena Vista, FL


  • Amorphous selenium
  • indirect conversion X-ray imager
  • lateral structure
  • metal-semiconductor- metal photoconductor
  • photoconductive gain

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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