Open AccessPerformance evaluation of a new 30 μm thick GaAs x-ray detector grown by MBE
Author(s) -
G. Lioliou,
Caroline L. Poyser,
Josh Whale,
R. P. Campion,
A. J. Kent,
A. M. Barnett
Publication year - 2021
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/abe73c
Subject(s) - full width at half maximum , molecular beam epitaxy , fabrication , optoelectronics , materials science , detector , wafer , photodiode , x ray detector , leakage (economics) , epitaxy , dark current , optics , layer (electronics) , photodetector , physics , nanotechnology , medicine , alternative medicine , pathology , economics , macroeconomics
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.