Total ionizing dose effects on the SOI pixel sensor for X-ray astronomical use

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2019-04, Vol.924, p.473-479
• Main Authors: Mori, Koji, Nishioka, Yusuke, Takeda, Ayaki, Takebayashi, Nobuaki, Takenaka, Ryota, Sakakura, Seina, Yokoyama, Shoma, Fukuda, Kohei, Yukumoto, Masataka, Hida, Takahiro, Tsuru, Takeshi G., Tanaka, Takaaki, Matsumura, Hideaki, Hayashi, Hideki, Kohmura, Takayoshi, Nakashima, Shinya, Arai, Yasuo, Kurachi, Ikuo
• Format: Article
• Language: English
• Subjects: CMOS; Imaging spectroscopy; SOI; TID; X-ray; XRPIX
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2018.07.057

We report on total ionizing dose effects on the X-ray SOI pixel sensor, XRPIX. XRPIX has been developed as an imaging spectrometer for X-ray astronomical use in space. Front- and back-illuminated (FI and BI) devices were irradiated with hard X-rays from an X-ray tube operated at 30 kV with a Molybdenum target. We found that the degradation rate of the readout noise of the BI device was approximately three times slower than that of the FI device as a function of radiation exposure. Those of both type of devices, however, were virtually identical when the readout noise was evaluated as a function of the absorbed dose at the buried oxide layer, DBOX. The pedestal and analog-to-digital conversion gain also displayed similar tendencies. These results demonstrate that BI type devices have a higher radiation tolerance as a focal plane sensor of an X-ray mirror and the radiation tolerance of XRPIX devices is governed by DBOX. The readout noise was stable up to about 1 krad in DBOX, increased by about 10% at 10 krad in DBOX, and continued to increase under further irradiation. If we employ an X-ray mirror with a half-power diameter of 10 arcsec and a focal length of 10 m, 10 krad in DBOX, a reasonable threshold of radiation tolerance in this experiment, is equivalent to more than three years in orbit, typically required of space-borne sensors. •Total ionizing dose effects on the SOI pixel sensor, XRPIX, were studied.•Front-and back-illuminated (FI and BI) devices were irradiated with hard X-rays.•BI type devices have a higher radiation tolerance.•XRPIX’s radiation tolerance is governed by the absorbed dose at the BOX layer.•XRPIX has a lifetime in orbit long enough for application as a space-borne sensor.