JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 7, 198–210 (1997) ARTICLE NO . XR970253 Electric Field Dependence on Charge Collection of CdZnTe X-Ray Detectors G. C. Giakos,* B. Pillai,* S. Vedantham,* S. Chowdhuri,* J. Odogba,* A. Dasgupta,* V. Vega-Lozada,* R. Guntupalli,* S. Suryanarayanan,* R. J. Endorf,² A. Passalaqua,‡ and S. Kollipara§ * Department of Biomedical Engineering, University of Akron, Akron, Ohio 44325; ² Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221; ‡ Department of Radiology, Northeastern Ohio Universities College of Medicine (NEOUCOM), Rootstown, Ohio 44272; and § Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 Received February 4, 1997; revised April 25, 1997 In this study, the electric field dependence on the charge collection process of CdZnTe detectors, at different x-ray tube settings, within the x-ray diagnostic energy range, is investigated. In addition, the detector contrast at different applied bias voltages and x- ray tube settings have been experimentally determined. The experimental results sug- gest that an efficient charge collection process is obtained by increasing the applied bias voltage. Once the applied bias voltage is sufficiently high, charge collection becomes complete and the detector operates in the saturation region. This is a prerequisite for high contrast and spatial resolution. As a result, the detector contrast is enhanced significantly. Therefore, CdZnTe detectors appear to be potential candidates for digital radiographic applications.  1997 Academic Press I. INTRODUCTION Different detector technologies and beam geometries have been proposed for digital radiography ( 1–9 ). Some of the disadvantages presently faced relate to the relatively high initial cost of digital radiographic systems, as well as to limited detector resolution, although rapid advances are being made. The detector system design criteria are aimed at increasing spatial resolution, temporal resolution and contrast resolution, detective quantum efficiency (DQE) and the signal-to-noise ratio, while maintaining sufficient sampling rates. A careful design and development of the detector has a beneficial impact on x-ray absorption and efficient conversion into charge carriers. 198 0895-3996/97 $25.00 Copyright  1997 by Academic Press All rights of reproduction in any form reserved.