Physics MSc Thesis Defense Presented By Tristen T. Thibault

Event Date: 
Thursday, December 8, 2022 - 1:00pm EST
Event Location: 
CB 4056
Event Contact Name: 
Dr. Alla Reznik / Dr. Gautam Das
Event Contact E-mail: 

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The Department of Physics Invites You To Attend A Master of Science
Thesis Defense Presented By:

"Dark current modeling and characterization of amorphous lead oxide-based x-ray 
photoconductive devices for application in x-ray medical imaging" 
Supervisor: Dr. A. Reznik

Thursday, December 8, 2022
in CB 4056 at 1:00 PM or Zoom
(Contact or for link and password)


The reduction of the dark current (DC) to a tolerable level in X-ray photoconductors is one of the key factors for their application as X-ray-to-charge transducers in the direct conversion flat panel X-ray imagers (FPXIs). Here, we discuss the origins of DC in an X-ray-to-charge transducer that is based on one of the most promising X-ray photoconductors: amorphous lead oxide (a-PbO). The transient DC in an a-PbO blocking structure is measured at different applied electric fields (5–20 V/μm). The experimental results are used to develop a theoretical model describing the electric field-dependent transient behavior of DC. We show that DC decay is caused by charge accumulation in deep localized states (traps) within the blocking layer. Accounting for the field-induced charge carrier release from traps, enhanced by charge hopping transitions, yields an excellent fit between the experimental and simulated results, thus clarifying the dynamic process of reaching a steady-state occupancy level of the deep localized states in the blocking layer. The model can be used to find an approximate optimal thickness of blocking layers for future iterations of a-PbO – based detectors without the need for time and labor-intensive experimental trial and error.