Ulrich Dr. Schiebel

Deep trapping and recombination in a-Se:As X-ray sensitive photoreceptors

Abstract Memory effects in selenium based X-ray detectors are related to the dynamics of charge storage and release in deep gap states of the material. The quantitative analysis of the X-ray induced effects provides additional information on the density of states near midgap, the formation of metastable deep traps and, especially, on the recombination of trapped and free charge carriers.

X-Ray Sensing Properties of a Lead Oxide Photoconductor Combined With an Amorphous Silicon Tft Array

We present first results on the performance of flat dynamic x-ray detectors (FDXD) based on arrays of amorphous silicon thin film transistors (TFT) with charge storage capacitances and lead oxide as x-ray photoconductor. In order to increase the “active area” of every pixel, the layout of the array has been made in a multilevel arrangement, where the charge collecting electrode is separated from the underlying electronics by a thick insulating layer. This allows for a geometrical overlap of the pixel electrodes and TFTs. PbO has been chosen as the x-ray sensing material due to its very high x-ray sensitivity. The relevant detector properties of evaporated PbO layers are described along with results obtained on first FDXD devices with PbO.