Development and Performance of Kyoto's X-ray Astronomical SOI pixel (SOIPIX) sensor

TL;DR

This paper reports on the development of Kyoto's X-ray SOIPIX sensors, highlighting their high energy resolution, fast timing, and thick depletion layer, advancing X-ray astronomy instrumentation.

Contribution

The paper introduces a fully depleted SOI-based monolithic pixel sensor with microsecond timing and wide energy coverage for next-generation X-ray astronomy.

Findings

Achieved 300 eV energy resolution at 6 keV

Demonstrated event-driven readout mode

Produced 500 μm thick depletion layer

Abstract

We have been developing monolithic active pixel sensors, known as Kyoto's X-ray SOIPIXs, based on the CMOS SOI (silicon-on-insulator) technology for next-generation X-ray astronomy satellites. The event trigger output function implemented in each pixel offers microsecond time resolution and enables reduction of the non-X-ray background that dominates the high X-ray energy band above 5--10 keV. A fully depleted SOI with a thick depletion layer and back illumination offers wide band coverage of 0.3--40 keV. Here, we report recent progress in the X-ray SOIPIX development. In this study, we achieved an energy resolution of 300~eV (FWHM) at 6~keV and a read-out noise of 33~e- (rms) in the frame readout mode, which allows us to clearly resolve Mn-K$\alpha$ and K$\beta$. Moreover, we produced a fully depleted layer with a thickness of $500~{\rm \mu m}$. The event-driven readout mode has already been successfully demonstrated.