Over 90% QE Soft-X-ray CMOS Sensor

Japanese Applied Physics Express Journal publishes a paper "High-exposure-durability, high-quantum-efficiency (>90%) backside-illuminated soft-X-ray CMOS sensor" by Tetsuo Harada, Nobukazu Teranishi, Takeo Watanabe, Quan Zhou, Jan Bogaerts, and Xinyang Wang from University of Hyogo, Shizuoka University, and Gpixel.

"We develop a high-quantum-efficiency, high-exposure-durability backside-illuminated CMOS image sensor for soft-X-ray detection. The backside fabrication process is optimized to reduce the dead-layer thickness, and the Si-layer thickness is increased to 9.5 μm to reduce radiation damage. Our sensor demonstrates a high quantum efficiency of greater than 90% in the photon-energy range of 80–1000 eV. Further, its EUV-regime efficiency is ~100% because the dead-layer thickness is only 5 nm. The readout noise is as low as 2.5 e− rms and the frame rate as high as 48 fps, which makes the device practical for general soft X-ray experiments.

...we developed a new CMOS sensor with further improvements to the backside process to afford a thicker Si layer of 9.5 μm; we called this sensor the SP3 sensor. This soft-X-ray/EUV-regime SP3 image sensor is also based on the Gpixel BSI CMOS image sensor, GSENSE400SQBSI. ...We made two changes to the backside fabrication process for the SP3 relative to the SBSA: the silicon thickness was changed from 3.5 to 9.5 μm to suppress radiation damage, and that the implantation energy was decreased by one digit to reduce the non-sensitive-layer thickness. Our CMOS sensor adopts a rolling shutter and a high dynamic range (HDR) scheme using the double-conversion gain method, and has 2048 (H) × 2048 (V) 11 μm pixels. "

Thanks to NT for the link!