Lead oxide (PbO) is a candidate direct conversion material for medical X-ray applications. We produced various samples and detectors with thick PbO layers. X-ray performance data such as dark current, charge generation yield and temporal behavior were evaluated on small samples. The influence of the metal contacts was studied in detail. We also covered large a-Si thin-film transistor (TFT)-plates with PbO. Imaging results from a large detector with an active area of 18 cm 20 cm are presented. The detector has 960 1080 pixels with a pixel pitch of 184 m. The modulation transfer function at the Nyquist frequency of 2.72 linepairs/mm is 50%. Finally, a full size X-ray image is presented.

Lead oxide (PbO) is a candidate direct conversion material for medical X-ray applications. We produced various samples and detectors with thick PbO layers. X-ray performance data such as dark current, charge generation yield and temporal behavior were evaluated on small samples. The influence of the metal contacts was studied in detail. We also covered large a-Si thin-film transistor (TFT)-plates with PbO. Imaging results from a large detector with an active area of 18 cm × 20 cm are presented. The detector has 960 × 1080 pixels with a pixel pitch of 184 ?m. The modulation transfer function at the Nyquist frequency of 2.72 linepairs/mm is 50%. Finally, a full size X-ray image is presented

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Electron-trapping-triggered anneal of defect states in silicon-rich hydrogenated amorphous silicon nitride Current transport and instability mechanisms in thin film diodes with nonstoichiometric silicon nitride (a-SiN x :H) semiconducting layers have been investigated. In common with amorphous silicon thin film transistors the electrical characteristics of these diodes have been found to drift during use. We found that the initial current-voltage characteristics are related to the choice of interfacial treatments. This is explained by trapping of electrons at interface defect states and by tunneling of electrons into the conduction band via these states. We have also found a relationship between the initial characteristics of the diodes and the rate of drift due to electrical stressing. A threshold exists below whose drift is independent of the current-voltage characteristics and above which there is a strong dependence. This dependence of drift on current-voltage characteristic is consistent with field enhanced defect creation in the a-SiN x :H layer.