Quantification of Trace-Level Silicon Doping in AlxGa1-xN Films Using Wavelength-Dispersive X-Ray Microanalysis
L. Spasevski1, B. Buse2, P.R. Edwards1, D.A. Hunter1, J. Enslin3, H.M. Foronda3, T. Wernicke3, F. Mehnke3, P.J. Parbrook4, M. Kneissl3,5, and R.W. Martin1
Published in:
Microsc. Microanal., vol. 27, no. 4, pp. 696-704, doi:10.1017/S1431927621000568 (2021).
Abstract:
Wavelength-dispersive X-ray (WDX) spectroscopy was used to measure silicon atom concentrations in the range 35-100 ppm [corresponding to (3-9) × 1018 cm-3] in doped AlxGa1-xN films using an electron probe microanalyser also equipped with a cathodoluminescence (CL) spectrometer. Doping with Si is the usual way to produce the n-type conducting layers that are critical in GaN- and AlxGa1-xN-based devices such as LEDs and laser diodes. Previously, we have shown excellent agreement for Mg dopant concentrations in p-GaN measured by WDX with values from the more widely used technique of secondary ion mass spectrometry (SIMS). However, a discrepancy between these methods has been reported when quantifying the n-type dopant, silicon. We identify the cause of discrepancy as inherent sample contamination and propose a way to correct this using a calibration relation. This new approach, using a method combining data derived from SIMS measurements on both GaN and AlxGa1-xN samples, provides the means to measure the Si content in these samples with account taken of variations in the ZAF corrections. This method presents a cost-effective and time-saving way to measure the Si doping and can also benefit from simultaneously measuring other signals, such as CL and electron channeling contrast imaging.
1 Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, UK
2 School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
3 Institute of Solid State Physics, Technische Universität Berlin, Berlin D-10623, Germany
4 Tyndall National Institute, University College Cork, Cork T12 R5CP, Ireland
5 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin D-12489, Germany
Keywords:
electron probe microanalysis, secondary ion mass spectrometry, semiconductor analysis, silicon doping, trace-element analysis
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America.
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
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