Characterization of Screen-Printed Mercuric Iodide Photoconductors for Mammography

We describe energy-dependent incomplete signal generation in semiconductor detectors with a simple planar geometry using deep charge trapping and depth-of-interaction models. Based on this formalism, we have characterized mercuric iodide ( HgI2) photoconductors by extracting performance parameters from x-ray-induced signals under mammographic imaging conditions. The HgI2 sample photoconductors were prepared using a simple screen-printing method. For an x-ray tube output from tungsten target and 30-kV setting, the quantum absorption efficiency of samples with a thickness of approximately 0.1 mm was measured to be ~ 70%. X-ray sensitivity was measured to be 0.4 nC cm ^{- 2} mR ^{- 1}. Mobility-lifetime products for electrons and holes were measured as ~ 2 ×10 ^{- 6} cm² V ^{- 1} and ~ 0.9 ×10 ^{- 6} cm² V ^{- 1}, respectively. Considering incomplete charge collection, the W-value (or w) was estimated to be ~ 27 eV. Since the characterization method described in this study is simple and does not require sophisticated equipment, it can be useful for the characterization of photoconductor materials.