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Characterization of gallium arsenide X-ray mesa p-i-n photodiodes at room temperature

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posted on 2023-06-09, 00:08 authored by Grammatiki Lioliou, X Meng, J S Ng, Anna BarnettAnna Barnett
Two GaAs mesa p+-i-n+ photodiodes intended for photon counting X-ray spectroscopy, having an i layer thickness of 7 µm and diameter of 200 µm, have been characterized electrically, for their responsivity at the wavelength range 580 nm to 980 nm and one of them for its performance at detection of soft X-rays, at room temperature. Dark current and capacitance measurements as a function of applied forward and reverse bias are presented. The results show low leakage current densities, in the range of nA/cm2 at the maximum internal electric field (22 kV/cm). The unintentional doping concentration of the i layer, calculated from capacitance measurements, was found to be <1014 cm-3. Photocurrent measurements were performed under visible and near infrared light illumination for both diodes. The analysis of these measurements suggests the presence of a non-active (dead) layer (0.16 µm thickness) at the p+ side top contact interface, where the photogenerated carriers do not contribute to the photocurrent, possibly due to recombination. One of the diodes, D1, was also characterized as detector for room temperature photon counting X-ray spectroscopy; the best energy resolution achieved (FWHM) at 5.9 keV was 745 eV. The noise analysis of the system, based on spectra obtained at different shaping times and applied reverse biases, showed that the dominant source of noise is the dielectric noise. It was also calculated that there was at least (165±24) eV charge trapping noise at 0 V.

History

Publication status

  • Published

File Version

  • Published version

Journal

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

ISSN

0168-9002

Publisher

Elsevier

Volume

813

Page range

1-9

Department affiliated with

  • Engineering and Design Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2016-01-27

First Open Access (FOA) Date

2016-01-27

First Compliant Deposit (FCD) Date

2016-01-27

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