Quantification of Trace-Level Silicon Doping in Al x Ga 1-x N Films Using Wavelength-Dispersive X-Ray Microanalysis

Lucia Spasevski; Ben Buse; Paul R. Edwards; Daniel A. Hunter; Johannes Enslin; Humberto M. Foronda; Tim Wernicke; Frank Mehnke; Peter J. Parbrook; Michael Kneissl; Robert W. Martin

doi:10.1017/S1431927621000568

Quantification of Trace-Level Silicon Doping in Al x Ga 1-x N Films Using Wavelength-Dispersive X-Ray Microanalysis

Lucia Spasevski^*
, Ben Buse
, Paul R. Edwards
, Daniel A. Hunter
, Johannes Enslin
, Humberto M. Foronda
, Tim Wernicke
, Frank Mehnke
, Peter J. Parbrook
, Michael Kneissl
, Robert W. Martin^*

^*Corresponding author for this work

School of Earth Sciences

Research output: Contribution to journal › Article (Academic Journal) › peer-review

2 Citations (Scopus)

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.

Original language	English
Pages (from-to)	696-704
Number of pages	9
Journal	Microscopy and Microanalysis
Volume	27
Issue number	4
DOIs	https://doi.org/10.1017/S1431927621000568
Publication status	Published - 1 Aug 2021

Bibliographical note

Funding Information:
The authors thank Dr. Trevor Martin from IQE Europe Ltd., for providing additional GaN:Si samples, and to Drs. Vitaly Zubialevich, Pietro Pampili, and Duc Dinh from Tyndall National Institute for providing additional AlGaN:Si samples. We acknowledge Alison Chew of Loughborough Surface Analysis Ltd. for provision of D-SIMS measurement and discussion of the results. We thank Dr. Gunnar Kusch for useful discussion and advice. We thank Dr. Stacey Laing from the Department of Pure and Applied Chemistry, University of Strathclyde, for performing plasma cleaning of the samples. We would also like to show our gratitude to Mr. James Sweeney and Dr. Ian Watson from the Institute of Photonics, University of Strathclyde, for cleaning the samples with HF solution. This work was supported by the EPSRC project EP/N010914/1, “Nanoanalysis for Advanced Materials and Healthcare,” by the EU-FP7 programme “ALIGHT,” Science Foundation Ireland through SFI/10/IN.1/I2993 and Irish Photonic Integration Centre (SFI/12/RC/2276_2), and the European Space Agency. All data underpinning this publication are openly available from the University of Strathclyde KnowledgeBase at: https://doi.org/10.15129/aa61c668-99ca-4802-9013-ff5f15409240 .

Publisher Copyright:
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America.

Keywords

Key words electron probe microanalysis
secondary ion mass spectrometry
semiconductor analysis
silicon doping
trace-element analysis

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@article{c2f15c1cf0b3469e80157b2b6e64a547,

title = "Quantification of Trace-Level Silicon Doping in Al x Ga 1-x N Films Using Wavelength-Dispersive X-Ray Microanalysis",

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.",

keywords = "Key words electron probe microanalysis, secondary ion mass spectrometry, semiconductor analysis, silicon doping, trace-element analysis",

author = "Lucia Spasevski and Ben Buse and Edwards, \{Paul R.\} and Hunter, \{Daniel A.\} and Johannes Enslin and Foronda, \{Humberto M.\} and Tim Wernicke and Frank Mehnke and Parbrook, \{Peter J.\} and Michael Kneissl and Martin, \{Robert W.\}",

note = "Funding Information: The authors thank Dr. Trevor Martin from IQE Europe Ltd., for providing additional GaN:Si samples, and to Drs. Vitaly Zubialevich, Pietro Pampili, and Duc Dinh from Tyndall National Institute for providing additional AlGaN:Si samples. We acknowledge Alison Chew of Loughborough Surface Analysis Ltd. for provision of D-SIMS measurement and discussion of the results. We thank Dr. Gunnar Kusch for useful discussion and advice. We thank Dr. Stacey Laing from the Department of Pure and Applied Chemistry, University of Strathclyde, for performing plasma cleaning of the samples. We would also like to show our gratitude to Mr. James Sweeney and Dr. Ian Watson from the Institute of Photonics, University of Strathclyde, for cleaning the samples with HF solution. This work was supported by the EPSRC project EP/N010914/1, “Nanoanalysis for Advanced Materials and Healthcare,” by the EU-FP7 programme “ALIGHT,” Science Foundation Ireland through SFI/10/IN.1/I2993 and Irish Photonic Integration Centre (SFI/12/RC/2276\_2), and the European Space Agency. All data underpinning this publication are openly available from the University of Strathclyde KnowledgeBase at: https://doi.org/10.15129/aa61c668-99ca-4802-9013-ff5f15409240 . Publisher Copyright: Copyright {\textcopyright} The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America.",

year = "2021",

month = aug,

day = "1",

doi = "10.1017/S1431927621000568",

language = "English",

volume = "27",

pages = "696--704",

journal = "Microscopy and Microanalysis",

issn = "1431-9276",

publisher = "Oxford University Press",

number = "4",

}

TY - JOUR

T1 - Quantification of Trace-Level Silicon Doping in Al x Ga 1-x N Films Using Wavelength-Dispersive X-Ray Microanalysis

AU - Spasevski, Lucia

AU - Buse, Ben

AU - Edwards, Paul R.

AU - Hunter, Daniel A.

AU - Enslin, Johannes

AU - Foronda, Humberto M.

AU - Wernicke, Tim

AU - Mehnke, Frank

AU - Parbrook, Peter J.

AU - Kneissl, Michael

AU - Martin, Robert W.

N1 - Funding Information: The authors thank Dr. Trevor Martin from IQE Europe Ltd., for providing additional GaN:Si samples, and to Drs. Vitaly Zubialevich, Pietro Pampili, and Duc Dinh from Tyndall National Institute for providing additional AlGaN:Si samples. We acknowledge Alison Chew of Loughborough Surface Analysis Ltd. for provision of D-SIMS measurement and discussion of the results. We thank Dr. Gunnar Kusch for useful discussion and advice. We thank Dr. Stacey Laing from the Department of Pure and Applied Chemistry, University of Strathclyde, for performing plasma cleaning of the samples. We would also like to show our gratitude to Mr. James Sweeney and Dr. Ian Watson from the Institute of Photonics, University of Strathclyde, for cleaning the samples with HF solution. This work was supported by the EPSRC project EP/N010914/1, “Nanoanalysis for Advanced Materials and Healthcare,” by the EU-FP7 programme “ALIGHT,” Science Foundation Ireland through SFI/10/IN.1/I2993 and Irish Photonic Integration Centre (SFI/12/RC/2276_2), and the European Space Agency. All data underpinning this publication are openly available from the University of Strathclyde KnowledgeBase at: https://doi.org/10.15129/aa61c668-99ca-4802-9013-ff5f15409240 . Publisher Copyright: Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America.

PY - 2021/8/1

Y1 - 2021/8/1

N2 - 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.

AB - 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.

KW - Key words electron probe microanalysis

KW - secondary ion mass spectrometry

KW - semiconductor analysis

KW - silicon doping

KW - trace-element analysis

UR - https://www.scopus.com/pages/publications/85109272432

U2 - 10.1017/S1431927621000568

DO - 10.1017/S1431927621000568

M3 - Article (Academic Journal)

C2 - 34218838

AN - SCOPUS:85109272432

SN - 1431-9276

VL - 27

SP - 696

EP - 704

JO - Microscopy and Microanalysis

JF - Microscopy and Microanalysis

IS - 4

ER -

Quantification of Trace-Level Silicon Doping in Al x Ga 1-x N Films Using Wavelength-Dispersive X-Ray Microanalysis

Abstract

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Keywords

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