Progress in Development of Monolithic Active Pixel Detector for X-ray Astronomy with SOI CMOS Technology

AbstractWe have been developing an active pixel sensor for X-ray astronomy. In this paper, we report on the design and the characterizationof the recently-developed device named XRPIX1-FZ.We applied the high-resistivitySiwafer(∼7 kΩ cm) to the sensor layer for a thick depletion layer. The chemical-mechanical polishing, which we applied to smooth the rough backside of the Si wafer, successfully reduced the dark current. We used the single-pixel readout mode and achievedthe energy resolution of 260eVinFWHMat8keV.Moreover, we developed the 3 × 3pixel readout mode for the evaluation of split events and confirmed the full depletion of 250μm thick at thereverse-biasvoltageof30