Identifying chemical and physical changes in wide-gap semiconductors using real-time and near ambient-pressure XPS

Astley, Simon; Hu, Di; Hazeldine, Kerry; Ash, Johnathan; Cross, Rachel Elizabeth; Cooil, Simon; Allen, Martin W.; Evans, James E.; James, Kelvin; Venturini, Federica; Grinter, David C.; Ferrer, Pilar; Arrigo, Rosa; Held, Georg; Williams, G. T.; Evans, D. Andrew

doi:10.1039/d1fd00119a

Cited by 3 publications

(2 citation statements)

References 45 publications

(58 reference statements)

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“…Unfortunately, while the C1s simulations provide significant clarity, the number of overlapping components in C1s makes application of this library to C1s deconvolution uninformative for complex samples. A final consideration is that for most quantum sensing applications n-type doped diamond is required, however to obtain sufficient conductivity for high resolution XPS measurements we measure exclusively boron doped (p-type) diamond [46]. For multiple measured oxygen terminations, companion n-type diamonds underwent the same surface treatments and were measured in NEXAFS, which does not require conductive samples.…”

Section: Discussionmentioning

confidence: 99%

X-ray quantification of oxygen groups on diamond surfaces for quantum applications

Dontschuk,

Rodgers,

Chou

et al. 2023

Mater. Quantum. Technol.

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Identifying the surface chemistry of diamond materials is increasingly important for device applications, especially quantum sensors. Oxygen-related termination species are widely used because they are naturally abundant, chemically stable, and compatible with stable nitrogen vacancy centers near the diamond surface. Diamond surfaces host a mixture of oxygen-related species, and the precise chemistry and relative coverage of diﬀerent species can lead to dramatically diﬀerent electronic properties, with direct consequences for near-surface quantum sensors. However, it is challenging to unambiguously identify the diﬀerent groups or quantify the relative surface coverage. Here we show that a combination of X-ray absorption and photoelectron spectroscopies can be used to quantitatively identify the coverage of carbonyl functional groups on the {100} diamond surface. Using this method we reveal an unexpectedly high fraction of carbonyl groups (> 9%) on a wide range of sample surfaces. Furthermore, through a combination of ab initio calculations and spectroscopic studies of engineered surfaces, we reveal unexpected complexities in the X-ray spectroscopy of oxygen terminated diamond surfaces. Of particular note, we ﬁnd the binding energies of carbonyl-related groups on diamond diﬀers signiﬁcantly from other organic systems, likely resulting in previous widespread misestimation of carbonyl fractions on diamond surfaces.

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Section: Discussionmentioning

confidence: 99%

X-ray quantification of oxygen groups on diamond surfaces for quantum applications

Dontschuk,

Rodgers,

Chou

et al. 2023

Mater. Quantum. Technol.

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“…Such a material also exhibited a crystalline lead halide degradation phase, caused by iodine migration from the perovskite, in a scanning nano X-ray diffraction experiment (Ferrer Orri et al, 2022). Further, radiation damage under X-ray exposure was studied for inorganic materials (metal alloy, oxide and semiconducting) with X-ray photon spectroscopy (Astley et al, 2022). Changes in the binding energies were identified for all three materials, but due to different reasons, for example thermal expansion of the metal alloy.…”

Section: Introductionmentioning

confidence: 99%

Beam-induced redox chemistry in iron oxide nanoparticle dispersions at ESRF–EBS

Thomä¹,

Zobel²

2023

J Synchrotron Radiat

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The storage ring upgrade of the European Synchrotron Radiation Facility makes ESRF–EBS the most brilliant high-energy fourth-generation light source, enabling in situ studies with unprecedented time resolution. While radiation damage is commonly associated with degradation of organic matter such as ionic liquids or polymers in the synchrotron beam, this study clearly shows that highly brilliant X-ray beams readily induce structural changes and beam damage in inorganic matter, too. Here, the reduction of Fe3+ to Fe2+ in iron oxide nanoparticles by radicals in the brilliant ESRF–EBS beam, not observed before the upgrade, is reported. Radicals are created due to radiolysis of an EtOH–H2O mixture with low EtOH concentration (∼6 vol%). In light of extended irradiation times during insitu experiments in, for example, battery and catalysis research, beam-induced redox chemistry needs to be understood for proper interpretation of insitu data.

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Surface states of photoelectrodes by surface-specific steady-state and time-resolved sum frequency spectroscopies

Zhang,

Brown,

Fisher

et al. 2024

Chinese Journal of Chemical Physics

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The surface states of photoelectrodes as catalysts heavily influence their performance in photocatalysis and photoelectrocatalysis applications. These catalysts are necessary for developing robust solutions to the climate and global energy crises by promoting CO2 reduction, N2 reduction, contaminant degradation, and water splitting. The semiconductors that can fill this role are beholden as photoelectrodes to the processes of charge generation, separation, and utilization, which are in turn products of surface states, surface electric fields, and surface carrier dynamics. Methods which are typically used for studying these processes to improve semiconductors are indirect, invasive, not surface specific, not practical under ambient conditions, or a combination thereof. Recently, nonlinear optical processes such as electronic sum-frequency generation (ESFG) and second-harmonic generation (ESHG) have gained popularity in investigations of semiconductor catalysts systems. Such techniques possess many advantages of in-situ analysis, interfacial specificity, non-invasiveness, as well as the ability to be used under any conditions. In this review, we detail the importance of surface states and their intimate relationship with catalytic performance, outline methods to investigate semiconductor surface states, electric fields, and carrier dynamics and highlight recent contributions to the field through interface-specific spectroscopy. We will also discuss how the recent development of heterodyne-detected ESHG (HD-ESHG) was used to extract charged surface states through phase information, time-resolved ESFG (TR-ESFG) to obtain in-situ dynamic process monitoring, and two-dimensional ESFG (2D-ESFG) to explore surface state couplings, and how further advancements in spectroscopic technology can fill in knowledge gaps to accelerate photoelectrocatalyst utilization. We believe that this work will provide a valuable summary of the importance of semiconductor surface states and interfacial electronic properties, inform a broad audience of the capabilities of nonlinear optical techniques, and inspire future original approaches to improving photocatalytic and photoelectrocatalytic devices.

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Identifying chemical and physical changes in wide-gap semiconductors using real-time and near ambient-pressure XPS

Abstract: The temperature-dependence of photoemission from a gold alloy, n-type β-Ga2O3 and p-type diamond reveals reversible and irreversible changes in energy, due to changes in surface chemistry, band-bending, thermal expansion and a surface photovoltage.

Cited by 3 publications

References 45 publications

X-ray quantification of oxygen groups on diamond surfaces for quantum applications

X-ray quantification of oxygen groups on diamond surfaces for quantum applications

Beam-induced redox chemistry in iron oxide nanoparticle dispersions at ESRF–EBS

Surface states of photoelectrodes by surface-specific steady-state and time-resolved sum frequency spectroscopies

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