Optimization of the i-layer width of Cr-a-Si : H PIN X-ray detectors

The influence of increasing the i-layer width of thick PIN a-Si:H diodes on the efficiency of X-ray detectors is analyzed. It is demonstrated that inc reasing the i-layer width to increase the interaction probability of the X- rays with the detector requires higher bias to achieve satisfactory collect ion efficiency. This higher bias produces, at the same time, an increase in the dark current that substantially decreases the overall detection effici ency. The use of complementary metal conversion layers is discussed and rec ommended and a Cr-a-Si:H PIN X-ray detector is fabricated and characterized . Experimental results are presented to validate expected behavior and reco mmended approach to increase the overall efficiency. (C) 2001 Elsevier Scie nce BY. All rights reserved.