X-ray Performance of Back-Side Illuminated Type of Kyoto's X-ray Astronomical SOI Pixel Sensor, XRPIX

TL;DR

This paper evaluates the soft X-ray detection performance of newly developed back-side illuminated XRPIX sensors, which are designed for wide-band X-ray astronomy and overcome limitations of front-illuminated sensors.

Contribution

It introduces and tests two types of back-side illuminated XRPIX sensors with reduced dead layers for improved low-energy X-ray detection.

Findings

Successful detection of soft X-rays down to 0.5 keV

Comparison of performance between two fabrication processes

Enhanced sensitivity achieved with back-side illumination

Abstract

We have been developing X-ray SOI pixel Sensors, called "XRPIX", for future X-ray astronomy satellites that enable us to observe in the wide energy band of 0.5-40 keV. Since XRPIXs have the circuitry layer with a thickness of about 8 {\mu}m in the front side of the sensor, it is impossible to detect low energy X-rays with a front-illuminated type. So, we have been developing back-illuminated type of XRPIX with a less 1 {\mu}m dead layer in the back-side, which enables the sensitivity to reach 0.5 keV. We produced two types of back-side illuminated (BI) XRPIXs, one of which is produced in "Pizza process" which LBNL developed and the other is processed in the ion implantation and laser annealing. We irradiated both of the BI-XRPIXs with soft X-ray and investigate soft X-ray performance of them. We report results from soft X-ray evaluation test of the device.