Inelastic background modelling applied to hard X-ray photoelectron spectroscopy of deeply buried layers: A comparison of synchrotron and lab-based (9.25 keV) measurements

Spencer, Ben F.; Maniyarasu, Suresh; Reed, Benjamen P.; Cant, David J. H.; Ahumada-Lazo, Rubén; Thomas, Andrew G.; Muryn, Christopher A.; Maschek, M.; Eriksson, Stefan; Wiell, T.; Lee, T.-L.; Tougaard, S.; Shard, Alexander G.; Flavell, Wendy R.

doi:10.1016/j.apsusc.2020.148635

Cited by 43 publications

(88 citation statements)

References 36 publications

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“…To complete this study, HAXPES offers the possibility to measure the bulk electronic properties and thus to probe, in a different manner than XPS, the perturbed depth inside the crater. A new generation of laboratory-based HAXPES spectrometers has already proved to be a new efficient route to characterize buried layers and bring chemical information through coatings (among them adventitious surface contamination), stretching the limits of low energy lab sources (mainly Al and [7,9]. Figure 2 shows the superimposition of the wide scans obtained on the same InP reference sample with the conventional Al-Kα source and the new generation Ga-Kα source.…”

Section: Analysis Methodologymentioning

confidence: 99%

“…A novel laboratory-based HAXPES spectrometer (ScientaOmicron GmbH, Uppsala, Sweden) uses a Ga Kα (9.25 keV) X-ray source and high electron kinetic energy analyzer [9], which has recently been benchmarked and elemental sensitivity factors calculated to enable quantification [7]. An Al Kα X-ray source is also attached and aligned to measure the same sample position; however, the Ga X-ray spot size is microfocussed to 50 µm in order to yield sufficient flux to overcome the associated decrease in photoionization cross section at higher photon energy.…”

Section: Haxpes and Xpsmentioning

confidence: 99%

“…The sampling depth is photoelectron kinetic energy dependent and may be calculated using the TPP-2M (Tanuma, Powell and Pen) formula [5,6]. For device structures with layers thinner than this maximal HAXPES (Hard X-ray PhotoElectron Spectroscopy) sampling depth, angle-resolved HAXPES may be used to increase the photoemission angle, θ, and reduce the sampling depth by a factor cos(θ), analogous to changing the photon energy at a synchrotron [7]. Additional core levels also become accessible and thus measuring different core levels in itself may provide an extended escape depth range.…”

Section: Introductionmentioning

confidence: 99%

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Combined Pulsed RF GD-OES and HAXPES for Quantified Depth Profiling through Coatings

et al. 2021

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Chemical characterization at buried interfaces is a real challenge, as the physico-chemical processes operating at the interface govern the properties of many systems and devices. We have developed a methodology based on the combined use of pulsed RF GD-OES (pulsed Radio Frequency Glow Discharge Optical Emission Spectrometry) and XPS (X-ray Photoelectron Spectroscopy) to facilitate the access to deeply buried locations (taking advantage of the high profiling rate of the GD-OES) and perform an accurate chemical diagnosis using XPS directly inside the GD crater. The reliability of the chemical information is, however, influenced by a perturbed layer present at the surface of the crater, hindering traditional XPS examination due to a relatively short sampling depth. Sampling below the perturbed layer may, however, can be achieved using a higher energy excitation source with an increased sampling depth, and is enabled here by a new laboratory-based HAXPES (Hard X-ray PhotoElectron Spectroscopy) (Ga-Kα, 9.25 keV). This new approach combining HAXPES with pulsed RF GD-OES requires benchmarking and is here demonstrated and evaluated on InP. The perturbed depth is estimated and the consistency of the chemical information measured is demonstrated, offering a new route for advanced chemical depth profiling through coatings and heterostructures.

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Section: Analysis Methodologymentioning

confidence: 99%

Section: Haxpes and Xpsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Combined Pulsed RF GD-OES and HAXPES for Quantified Depth Profiling through Coatings

et al. 2021

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“…[145][146][147][148] Inelastic background modelling has been explored to detect deeply buried layers beyond the elastic limit. [113,149] Whilst the IMFP finds wide application to estimate the probing depth in HAXPES, and generally in PES, it does not include effects from elastic scattering, which can play a significant role in determining the information depth, depending on excitation energy and atomic number. When elastic scattering effects are important, the effective attenuation length (EAL) is used instead of the IMFP, which gives smaller information depths due to losses from elastic scattering.…”

Section: Exploring Multiple Dimensions With Haxpes -Available Experimental Modimentioning

confidence: 99%

“…As expected, an increase in photoemission angle decreases the sampling depth, analogous to reducing the photon energy. [113] 3.1.6. Hard X-ray photoemission electron microscopy (HAXPEEM) Photoemission electron microscopy provides a magnified image of the lateral intensity distribution of photoelectrons emitted by a sample.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Hard x-ray photoelectron spectroscopy: a snapshot of the state-of-the-art in 2020

Kalha

Fernando

Bhatt

et al. 2021

J. Phys.: Condens. Matter

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Hard X-ray photoelectron spectroscopy (HAXPES) is establishing itself as an essential technique for the characterisation of materials. The number of specialised photoelectron spectroscopy techniques making use of hard X-rays is steadily increasing and ever more complex experimental designs enable truly transformative insights into the chemical, electronic, magnetic, and structural nature of materials. This paper begins with a short historic perspective of HAXPES and spans from developments in the early days of photoelectron spectroscopy to provide an understanding of the origin and initial development of the technique to state-of-the-art instrumentation and experimental capabilities. The main motivation for and focus of this paper is to provide a picture of the technique in 2020, including a detailed overview of available experimental systems worldwide and insights into a range of specific measurement modi and approaches. We also aim to provide a glimpse into the future of the technique including possible developments and opportunities.

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Improved depth information from routine analysis of the inelastic background of XPS and HAXPES spectra using optimized two‐ and three‐parameter cross‐sections

Zborowski

Tougaard

2021

Surface & Interface Analysis

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Determination of the depth distribution of complex nanostructures by X‐ray photoelectron spectroscopy (XPS) inelastic background analysis may be complicated if the sample materials have widely different inelastic scattering cross‐sections. It was recently demonstrated that this may be solved by using a mixture of cross‐sections. This permits retrieval of depth distributions of complex stacks and deeply buried layers with a typical 5% accuracy. This requires however that the cross‐sections of the individual sample materials are known which is often not the case and this can complicate practical use for routine analysis. In this paper, we explore to what extent a suitable two‐ or three‐parameter cross‐section can be defined independent of prior knowledge of the cross‐sections involved but simply defined by fitting the cross‐section parameters to the spectrum being analyzed. This paper presents a theoretical study following our recent paper that explored how to make the best choice of inelastic mean free path and inelastic scattering cross‐section for the inelastic background analysis with the Quases‐Tougaard software. It was previously shown that a rough analysis of the inelastic background could give a good idea of the depth distribution. Here, we demonstrate with model spectra from buried layers created with Quases‐Tougaard Generate software that a rather accurate analysis can be performed for very different cases with an average ~5% error. This analysis is easy to apply as it only needs the two‐ or three‐parameter cross‐sections generated with the Quases‐Tougaard software. This study is aimed to improve routine analysis of the inelastic background of XPS and hard X‐ray photoelectron spectroscopy (HAXPES) spectra.

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Inelastic background modelling applied to hard X-ray photoelectron spectroscopy of deeply buried layers: A comparison of synchrotron and lab-based (9.25 keV) measurements

Cited by 43 publications

References 36 publications

Combined Pulsed RF GD-OES and HAXPES for Quantified Depth Profiling through Coatings

Combined Pulsed RF GD-OES and HAXPES for Quantified Depth Profiling through Coatings

Hard x-ray photoelectron spectroscopy: a snapshot of the state-of-the-art in 2020

Improved depth information from routine analysis of the inelastic background of XPS and HAXPES spectra using optimized two‐ and three‐parameter cross‐sections

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