Development of X-ray SOI Pixel Sensors: Investigation of Charge-Collection Efficiency

Jun 5, 2014, 11:40 AM
Administratiezaal (Beurs van Berlage)


Beurs van Berlage

Oral Experiments: 2b) Astrophysics and Space Instrumentation II.b Astro & Space


Hideaki Matsumura (Kyoto University)


We have been developing X-ray SOIPIXs, monolithic active pixel sensors based on the Silicon-On-Insulator (SOI) CMOS technology for next-generation X-ray astronomy satellites. Their high time resolution (~micro sec) and event trigger output function enable us to reduce non-X-ray background by two orders of magnitude at 20 keV, compared with X-ray CCDs widely used in current X-ray astronomy sattelites. A fully depleted thick depletion layer with back-side illumination offers wide band coverage of ∼0.3–40 keV. We already achieved thick and full depletion layer with a thickness of 500 micron. We will report recent progress in our development in this presentation. We measured sub-pixel charge-collection efficiency of our device by irradiating it with pencil beam X-rays at SPring-8. We found that a part of signal charges is lost at the pixel boundaries. We found that the amount of the charge loss depends on back-bias voltages. It leads us to a hypothesis that the strength of electric fields at the interface between the sensor and silicon dioxide layers determines the charge collection efficiency. We will test the hypothesis by comparing the experimental results with TCAD simulations.

Primary author

Hideaki Matsumura (Kyoto University)


Ayaki Takeda (SOKENDAI) Ryota Takenaka (University of Miyazaki) Dr Shinya Nakashima (Kyoto University) Dr Takaaki Tanaka (Kyoto University) Takayoshi Kohmura (Kogakuin University) Takeshi Tsuru (Kyoto University) Yasuo Arai (High Energy Accelerator Research Organization (JP)) Yusuke Nishioka (University of Miyazaki) koji mori (University of Miyazaki)

Presentation materials