Energy resolution of amorphous selenium detectors: conventional vs unipolar charge sensing

In this study, we fabricated a pixelated unipolar charge sensing detector based on amorphous selenium with a 20-μm pixel pitch using standard lithography process. A pulse-height spectroscopy (PHS) setup with a very low noise front-end electronics was designed, and experiments were performed to investigate the achievable energy resolution with the unipolar detector, as well as with a conventional detector for comparison purposes. PHS measurement results are presented that demonstrate, for the first time, a measured energy resolution of 8.3 keV at 59.5 keV is for the unipolar charge sensing device in contrast to 14.5 keV at 59.5 keV for conventional a-Se devices, indicating its promise for the contrast-enhanced photon counting imaging with an unsurpassed spatial resolution.