Improvement of spectroscopic performance using a charge-sensitive amplifier circuit for an X-ray astronomical SOI pixel detector

A. Takeda, T.G. Tsuru, T. Tanaka, H. Uchida, H. Matsumura, Y. Arai, K. Mori, Y. Nishioka, R. Takenaka, T. Kohmura, S. Nakashima, S. Kawahito (+4 others)
2015 Journal of Instrumentation  
We have been developing monolithic active pixel sensors series, named "XRPIX," based on the silicon-on-insulator (SOI) pixel technology, for future X-ray astronomical satellites. The XRPIX series offers high coincidence time resolution (∼1 μs), superior readout time (∼10 μs), and a wide energy range (0.5--40 keV). In the previous study, we successfully demonstrated X-ray detection by event-driven readout of XRPIX2b. We here report recent improvements in spectroscopic performance. We
more » ... increased the gain and reduced the readout noise in XRPIX2b by decreasing the parasitic capacitance of the sense-node originated in the buried p-well (BPW). On the other hand, we found significant tail structures in the spectral response due to the loss of the charge collection efficiency when a small BPW is employed. Thus, we increased the gain in XRPIX3b by introducing in-pixel charge sensitive amplifiers instead of having even smaller BPW. We finally achieved the readout noise of 35 e ^- (rms) and the energy resolution of 320 eV (FWHM) at 6 keV without significant loss of the charge collection efficiency.
doi:10.1088/1748-0221/10/06/c06005 fatcat:bwsftnu3fzdc3fgld5u24srwpe