Mercuric iodide thick films for radiological x-ray detectors

For the first time polycrystalline HgI2 photoconductor material directly evaporated on a-Si array for direct conversion of x-rays for imaging purposes, were successfully imaged at Xerox-Palo Alto Research Center. The initial results are very promising and show a high x-ray sensitivity and low leakage current. Since Ti-W alloys are used as pixel electrodes, an intermediate passivation layer must be used to prevent a chemical reaction with the detector plate. The thickness that these Polycrystalline HgI2 thick film detectors have been fabricated until now is up to 1,800 micrometers , which makes them useful also for high energy applications. The characterization of the Polycrystalline HgI2 thick films deposited with or without the passivation layers by measuring their dark currents, sensitivity to 65 and 85 kVp x-rays and residual signals after 1 minute of biasing, will be shown for several detectors. Some preliminary results will be shown for some novel screen-printed HgI2 detectors.