Amorphous selenium as an X-ray photoconductor

We report on electron and hole drift mobility, lifetime and range measurements on vacuum coated stabilized a-Se (a-Se alloyed with As and doped with Q X-ray photoconductor type layers as a function of the substrate temperature T-substrate during deposition; T-substrate has been varied from 6 to 66degreesC covering the glass transition temperature of a-Se (about 40degreesC). We find the electron mobility, lifetime and range show essentially no dependence on T-substrate, whereas for holes, although the drift mobility is not significantly affected, the lifetime deteriorates rapidly with decreasing T-substrate. We also re-examine and discuss the charge conversion efficiency of a-Se X-ray photoconductors by reanalyzing the electron-hole pair creation energy (W+/-) vs. field data, and evaluating the saturated (minimum) W+/- from the W+/- vs. reciprocal field plot. (C) 2004 Elsevier B.V. All rights reserved.