Quantum Efficiency Measurement and Modeling of Silicon Sensors Optimized for Soft X-ray Detection
Author:
Carulla Maria1ORCID, Barten Rebecca1, Baruffaldi Filippo1ORCID, Bergamaschi Anna1ORCID, Borghi Giacomo2ORCID, Boscardin Maurizio2, Brückner Martin1, Butcher Tim A.1ORCID, Centis Vignali Matteo2, Dinapoli Roberto1, Ebner Simon1, Ficorella Francesco2, Fröjdh Erik1ORCID, Greiffenberg Dominic1ORCID, Hammad Ali Omar2ORCID, Hasanaj Shqipe1, Heymes Julian1ORCID, Hinger Viktoria1ORCID, King Thomas1, Kozlowski Pawel1, Lopez Cuenca Carlos1, Mezza Davide1, Moustakas Konstantinos1, Mozzanica Aldo1ORCID, Paternoster Giovanni2, Paton Kirsty A.1ORCID, Ronchin Sabina2, Ruder Christian1, Schmitt Bernd1, Sieberer Patrick1ORCID, Thattil Dhanya1, Vogelsang Konrad1, Xie Xiangyu1, Zhang Jiaguo1ORCID
Affiliation:
1. Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland 2. Fondazione Bruno Kessler, Via Sommarive 18, 38126 Povo, Italy
Abstract
Hybrid pixel detectors have become indispensable at synchrotron and X-ray free-electron laser facilities thanks to their large dynamic range, high frame rate, low noise, and large area. However, at energies below 3 keV, the detector performance is often limited because of the poor quantum efficiency of the sensor and the difficulty in achieving single-photon resolution due to the low signal-to-noise ratio. In this paper, we address the quantum efficiency of silicon sensors by refining the design of the entrance window, mainly by passivating the silicon surface and optimizing the dopant profile of the n+ region. We present the measurement of the quantum efficiency in the soft X-ray energy range for silicon sensors with several process variations in the fabrication of planar sensors with thin entrance windows. The quantum efficiency for 250 eV photons is increased from almost 0.5% for a standard sensor to up to 62% as a consequence of these developments, comparable to the quantum efficiency of backside-illuminated scientific CMOS sensors. Finally, we discuss the influence of the various process parameters on quantum efficiency and present a strategy for further improvement.
Funder
MSCA PSI-FELLOW-III-3i Swiss Nanoscience Institute
Subject
Electrical and Electronic Engineering,Biochemistry,Instrumentation,Atomic and Molecular Physics, and Optics,Analytical Chemistry
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