Large-area x-ray image sensing using a Pbl 2 photoconductor

Abstract
We report the fabrication and evaluation of a Pbl2 imager using large area amorphous silicon technology. This approach uses a thick Pbl2 x-ray photoconductor to absorb x-rays and collect ionization charge under the action of an applied field, while amorphous silicon thin film transistors (TFT) provide a matrix-addressed read out of the signal to external electronics. The x-ray sensitivity of Pbl2 is high, and mobility-lifetime product is large enough to yield a high charge collection at low applied fields. The test arrays used to evaluate Pbl2 have 256 X 256 pixels of size 200 microns. Each pixel contains an amorphous silicon switching transistor, gate and data addressing lines, a charge storage capacitor and a metal pad to contact the Pbl2 layer. Early evaluation of the image sensor indicates the promise of Pbl2 but indicates that reduction of the leakage current is important.