Performance evaluation of a new 30 μm thick GaAs x-ray detector grown by MBE

Lioliou, G, Poyser, C L, Whale, J, Campion, R P, Kent, A J and Barnett, A M (2021) Performance evaluation of a new 30 μm thick GaAs x-ray detector grown by MBE. Materials Research Express, 8 (2). a025909 1-6. ISSN 2053-1591

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A circular mesa (400 μm diameter) GaAs p+-i-n+ photodiode with a 30 μm thick i layer was characterized for its performance as a detector in photon counting x-ray spectroscopy at 20 °C. The detector was fabricated from material grown by molecular beam epitaxy (MBE). An earlier MBE-grown detector fabricated using a different fabrication process and material from a different area of the same epiwafer was shown to suffer from: relatively high leakage current at high temperatures; a high effective carrier concentration that limited its depletion layer width; and material imperfections (butterfly defects) [Lioliou et al 2019 Nucl. Instrum. Methods Phys. Res. A 946 162670]. However, the new detector has better performance (lower leakage current and effective carrier concentration within the i layer). Using the new detector and low noise readout electronics, an energy resolution of 750 eV ± 20 eV Full Width at Half Maximum (FWHM) at 5.9 keV was achieved at 20 °C, equal to that reported for high quality GaAs detectors made from high quality material grown by metalorganic vapour phase epitaxy [Lioliou et al 2017 J. Appl. Phys. 122 244506]. The results highlight the substantially different performances of detectors made from the same epiwafer when the wafer qualities are not uniform and the effects of different fabrication processes.

Item Type: Article
Keywords: x-ray spectroscopy, photodiode, gallium arsenide, molecular beam epitaxy
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Space Research Group
Subjects: Q Science > QC Physics
Depositing User: Grammatiki Lioliou
Date Deposited: 03 Mar 2021 08:11
Last Modified: 24 Nov 2021 17:48

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