Al0.2Ga0.8As X-ray photodiodes for X-ray spectroscopy

Whitaker, M D C, Lioliou, G, Butera, S and Barnett, A M (2016) Al0.2Ga0.8As X-ray photodiodes for X-ray spectroscopy. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 840. pp. 168-173. ISSN 0168-9002

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Abstract

Three custom-made Al0.2Ga0.8As p-i-n mesa X-ray photodiodes (200 µm diameter, 3 µm i layer) were electrically characterised and investigated for their response to illumination with soft X-rays from an 55Fe radioisotope X-ray source (Mn Kα = 5.9 keV; Mn Kβ = 6.49 keV). The AlGaAs photodiodes were shown to be suitable for photon counting X-ray spectroscopy at room temperature. When coupled to a custom-made low-noise charge-sensitive preamplifier, a mean energy resolution (as quantified by the full width at half maximum of the 5.9 keV photopeak) of 1.24 keV was measured at room temperature. Parameters such as the depletion width (1.92 µm at 10 V), charge trapping noise (61.7 e− rms ENC at 5 V, negligible at 10 V) and the electronic noise components (known dielectric noise (63.4 e− rms), series white noise (27.7 e− rms), parallel white noise (9.5 e− rms) and 1/f series noise (2.2 e− rms) at 10 V reverse bias) affecting the achieved energy resolution were computed. The estimated charge trapping noise and mean energy resolution were compared to similar materials (e.g. Al0.8Ga0.2As) previously reported, and discussed. These results are the first demonstration of photon counting X-ray spectroscopy with Al0.2Ga0.8As reported to date.

Item Type: Article
Keywords: X-ray detector; Photodiode; Spectroscopy
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Research Centres and Groups: Sensor Technology Research Centre
Subjects: Q Science > QC Physics > QC0170 Atomic physics. Constitution and properties of matter Including molecular physics, relativity, quantum theory, and solid state physics
Q Science > QC Physics > QC0474 Radiation physics (General)
Depositing User: Michael Whitaker
Date Deposited: 19 Oct 2016 12:05
Last Modified: 09 Aug 2017 17:04
URI: http://sro.sussex.ac.uk/id/eprint/64896

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