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Progress in the science and technology of direct conversion X-ray image detectors: The development of a double layer a-Se based detector

S. O. KASAP1,* , G. BELEV1

Affiliation

  1. Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, S7N 5A9, Canada

Abstract

One very important requirement for an X-ray photoconductor to be usable in a practical detector is that the dark current at the operating field should be as low as possible. We examine, in terms of an order of magnitude calculations, the maximum allowed dark current density, which is ~10 pA mm-2. Dark currents in presently competing X-ray photoconductors are compared and discussed. We pay particular attention to a-Se based photoconductors inasmuch as the progress in the science and technology of a-Se based detectors has led to their commercialization. We report and discuss dark current measurements on single and double layer a-Se based photoconductor structures, and show how these measurements paved the way to the development of a new a-Se based X-ray detector fabricated on a CCD that is suitable for slot scanned X-ray imaging. The a-Se CCD detector has provided excellent images, and has a remarkable high resolution, better than 16 lines mm-1..

Keywords

X-ray photoconductors, X-ray detectors, a-Se alloys, Dark current, a-Se, HgI2, PbO, CdZnTe.

Submitted at: Nov. 2, 2006
Accepted at: Jan. 15, 2007

Citation

S. O. KASAP, G. BELEV, Progress in the science and technology of direct conversion X-ray image detectors: The development of a double layer a-Se based detector, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 1, pp. 1-10 (2007)