22 March 2010 Amorphous selenium lateral Frisch photodetector and photomultiplier for high performance medical x-ray and gamma-ray imaging applications
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Abstract
We propose a new indirect x-ray and gamma-ray detector which is comprised of a scintillating crystal coupled with an amorphous selenium (a-Se) metal-semiconductor-metal (MSM) photodetector. A lateral Frisch grid is embedded between the anode and the cathode to provide (1) unipolar charge sensing and (2) avalanche multiplication gain during hole transport inside the detection region. Unipolar charge sensing operation reduces the persistent photocurrent lag and increases the speed of the photodetector because most of the pixel charge is induced during carrier transport inside the detection region. Also, with proper biasing of the electrodes, we can create a high-field region between the lateral Frisch grid and the cathode for avalanche multiplication gain. Thus, we can convert the photodetector into a photomultiplier for higher signal-to-noise ratio and single photon-counting gamma-ray imaging. We present for the first time, a fabricated amorphous selenium lateral Frisch photodetector and present preliminary results of the measured photocurrents in response to a blue light emitting diode.
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A. H. Goldan, A. H. Goldan, K. Wang, K. Wang, F. Chen, F. Chen, K. S. Karim, K. S. Karim, } "Amorphous selenium lateral Frisch photodetector and photomultiplier for high performance medical x-ray and gamma-ray imaging applications", Proc. SPIE 7622, Medical Imaging 2010: Physics of Medical Imaging, 76223R (22 March 2010); doi: 10.1117/12.844809; https://doi.org/10.1117/12.844809
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