Polycrystalline Mercuric Iodide Films on CMOS Readout Arrays

We have created high-resolution x-ray imaging devices using polycrystalline mercuric iodide (HgI2) films grown directly onto CMOS readout chips using a thermal vapor transport process. Images from prototype 400 x 400 pixel HgI2 coated CMOS readout chips are presented, where the pixel grid is 30 mu m x 30 mu m. The devices exhibited sensitivity of 6.2 mu C/Rcm(2) with corresponding dark current of similar to 2.7 nA/cm(2), and a 80 mu m FWHM planar image response to a 50 mu m slit aperture. X-ray CT images demonstrate a point spread function sufficient to obtain a 50 mu m spatial resolution in reconstructed CT images at a substantially reduced dose compared to phosphor-coated readouts. The use of CMOS technology allows for small pixels (30 mu m), fast readout speeds (8 fps for a 3200 x 3200 pixel array), and future design flexibility due to the use of well-developed fabrication processes.