Polycrystalline lead iodide films for digital X-ray sensors

Polycrystalline lead iodide (PbI2) is one of only a few materials commonly mentioned as a potential direct converter for digital X-ray sensors. Previous evaluations have noted higher than desirable leakage currents and commented on imaging characteristics from sensors constructed with PbI2 films deposited onto amorphous Si thin film transistor arrays. Changes in film growth parameters show a significant reduction in leakage current, to 10's of pA/mm2 (or less than 1 pA/pixel). Sensitivity remains good but is limited by incomplete X-ray absorption and lag. Image samples are derived from two different a-Si TFT designs, demonstrating high resolution and good contrast.