X-ray absorption spectroscopy study on SiC-side interface structure of SiO<sub>2</sub>–SiC formed by thermal oxidation in dry oxygen

Isomura, Noritake; Kosaka, Satoru; Kataoka, Keita; Watanabe, Yukihiko; Kimoto, Yasuji

doi:10.7567/jjap.57.060308

Cited by 8 publications

(3 citation statements)

References 33 publications

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“…We studied surface-sensitive techniques of EXAFS by detecting Auger electrons escaping from sample surfaces (Isomura et al, 2016(Isomura et al, , 2017(Isomura et al, , 2018. EXAFS spectra are obtained during the energy sweep of the incident X-ray by monitoring the intensity of Auger electrons using the electron monochromator.…”

Section: Introductionmentioning

confidence: 99%

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

Isomura¹,

Kikuta²,

Takahashi³

et al. 2019

J Synchrotron Radiat

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GaN is a promising material for power semiconductor devices used in nextgeneration vehicles. Its electrical properties such as carrier mobility and threshold voltage are affected by the interface between the oxide and the semiconductor, and identifying the interface states is important to improve these properties. A surface-sensitive measurement of Ga K-edge extended X-ray absorption fine structure (EXAFS) by detecting Ga LMM Auger electrons that originate from Ga K-shell absorption is proposed for GaN. LMM Auger electrons with low energies were detected and the EXAFS oscillation was confirmed, providing information on the Ga atoms at the surface. Investigation of thermally oxidized GaN with an oxide film of defined thickness showed that the analysis depth was less than 10 nm, which is consistent with the inelastic mean free path of 2.3 nm estimated for LMM Auger electrons in GaN.

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Section: Introductionmentioning

confidence: 99%

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

Isomura¹,

Kikuta²,

Takahashi³

et al. 2019

J Synchrotron Radiat

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“…From the fitting, the coordination number and the Al–C distance were estimated to be 4.0 and 2.13 Å, respectively. Since the undoped SiC exhibits a coordination number of 4.0 and a Si–C bond length of 1.89 Å, the Al dopant atom increases the bond length around the dopant. , This may be due to the difference in atom size between the Al atom (radius: 0.125 nm) and the Si atom (radius: 0.111 nm) . The derivation of the bond length may be attributed to the relaxation of the local structure around the dopant Al atom.…”

Section: Resultsmentioning

confidence: 99%

X-ray Absorption Fine Structural Study of Atomic Structures and Chemical States of Dopants in 4H-SiC(0001)

Tsai

Tang

Yamashita

2023

ACS Appl. Electron. Mater.

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The atomic structures and chemical states of active and inactive dopant sites in n-type and p-type 4H-SiC(0001) substrates have been investigated by X-ray absorption near edge structure (XANES) and photoelectron spectroscopy (PES). In N atom-doped n-type 4H-SiC(0001), the PES results indicated that a N− C species was formed near the surface. XANES simulations showed that SiNx and N−C species were attributed to active and inactive dopant states, respectively. Angle-resolved XANES measurements showed that the N−C species acted as an inactive dopant site in N-doped 4H-SiC(0001). In Al-doped p-type 4H-SiC, PES analysis revealed that a single chemical state was present at the Al-doped 4H-SiC. The simulated XANES spectra showed that the Si site in 4H-SiC(0001) was replaced by an Al dopant atom, which was the active dopant site. Furthermore, relaxation of the local structure around the Al dopant in Al-doped 4H-SiC(0001) was observed due to bond stretching.

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“…Therefore, in general, HAXPES analysis uses X-rays from synchrotron radiation, which have high brightness. We used the Aichi Synchrotron Radiation Center (Aichi SR) BL6N1 (Yamamoto et al, 2014;Isomura et al, 2018) as our source for 3 keV radiation, the Super Photon Ring 8 GeV (SPring-8) BL16XU (Hirai et al, 2004;Isomura et al, 2019a) for 6 keV radiation, and SPring-8 BL46XU (Isomura et al, 2019b) for 10 keV radiation. Each light source consisted of quasi-monochromatic light, monochromatized using a double-crystal monochromator.…”

Section: Haxpes Analysismentioning

confidence: 99%

Non-destructive depth analysis of acidic phosphate ester boundary layers by hard X-ray photoelectron spectroscopy

TAKECHI-TAKAHASHI

MATSUSHIMA

Isomura

et al. 2022

JAMDSM

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Energy-resolved HAXPES is proposed here as a method to analyze boundary layer formation on rough frictional surfaces, in which the vertical OLAP boundary layer structure containing organic components is nondestructively analyzed. In addition, HAXPES analysis was performed with high incident X-ray energies to obtain information about the entire boundary layer, and to distinguish the organic and inorganic layers for calculating the effective thickness of each. The results revealed that the vertical structure of the OLAP boundary layer consists of a surface layer of organic molecules, including esters and phosphates, and an inorganic iron phosphate layer at the substrate interface, with each component exhibiting a vertical concentration gradient. Furthermore, the effective thickness of the organic layer formed under the present sliding conditions was estimated to be about 50 to 80 nm, which became thicker and exhibited lower friction at increased running-in times, and is greater than the inorganic layer thickness of 10 to 15 nm. It is reasonable to attribute the observed low-friction and velocitydependent properties to the thicker organic layer that preferentially supports the load during friction, demonstrating that this method is useful for determining the effects of boundary layers on tribological properties.

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X-ray absorption spectroscopy study on SiC-side interface structure of SiO₂–SiC formed by thermal oxidation in dry oxygen

Cited by 8 publications

References 33 publications

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

X-ray Absorption Fine Structural Study of Atomic Structures and Chemical States of Dopants in 4H-SiC(0001)

Non-destructive depth analysis of acidic phosphate ester boundary layers by hard X-ray photoelectron spectroscopy

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X-ray absorption spectroscopy study on SiC-side interface structure of SiO2–SiC formed by thermal oxidation in dry oxygen

Cited by 8 publications

References 33 publications

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

Local atomic structure analysis of GaN surfaces via X-ray absorption spectroscopy by detecting Auger electrons with low energies

X-ray Absorption Fine Structural Study of Atomic Structures and Chemical States of Dopants in 4H-SiC(0001)

Non-destructive depth analysis of acidic phosphate ester boundary layers by hard X-ray photoelectron spectroscopy

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X-ray absorption spectroscopy study on SiC-side interface structure of SiO₂–SiC formed by thermal oxidation in dry oxygen