Quantum Efficiency Measurement and Modeling of Silicon Sensors Optimized for Soft X-ray Detection

作者：Maria Carulla, R. Barten, F. Baruffaldi, A. Bergamaschi, G. Borghi, M. Boscardin, Martin Brückner, Tim A. Butcher, M. Centis Vignali, R. Dinapoli, Simon Ebner, F. Ficorella, E. Fröjdh, D. Greiffenberg, O. Hammad Alì, S. Hasanaj, Julian Heymes, V. Hinger, Thomas R. King, Pawel M. Kozlowski, Carlos Lopez Cuenca, D. Mezza, Konstantinos Moustakas, A. Mozzanica, G. Paternoster, Kirsty A. Paton, S. Ronchin, C. Ruder, Bernd Schmitt, P. Sieberer, D. Thattil, Konrad Vogelsang, Xiangyu Xie, Jiaguo Zhang · 发表于：Sensors · 年份：2024 · DOI：10.3390/s24030942 · 被引用次数：5 · 研究领域：Particle Detector Development and Performance、Advanced X-ray and CT Imaging、Medical Imaging Techniques and Applications

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.