X-ray-absorption spectroscopy of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CoSi</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Wf, Pong; Chang, Yun-Chi; Ra, Mayanovic; Gh, Ho; Hj, Lin; Sh, Ko; Pk, Tseng; Chen, CT; Hiraya, Atsunari; Watanabe, Makoto

doi:10.1103/physrevb.53.16510

Cited by 11 publications

(16 citation statements)

References 30 publications

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“…The threshold energy and general line-shape of the Si K -edge XANES spectra of the S-hyperdoped Si samples are similar to that of the reference Si(100). The characteristic double-peak feature (indicated by two dashed lines, denoted as feature A 2 ) of S-hyperdoped Si samples and reference Si(100) above the threshold and its approximate 1.1 eV energy separation are consistent with earlier studies 32 33 34 35 . Hitchcock et al .…”

Section: Resultssupporting

confidence: 89%

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

Limaye

Chen

Lee

et al. 2015

Sci Rep

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The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples.

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Section: Resultssupporting

confidence: 89%

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

Limaye

Chen

Lee

et al. 2015

Sci Rep

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“…All fluorescence measurements for the N K-edge x-ray absorption near edge structure ͑XANES͒ spectra were performed using a seven-element Ge detector. Photon energies for C, N, and Si K-edge XANES measurements were calibrated using the bulk diamond, 10 the well known CaF 2 thin film and the crystalline Si͑100͒ film, 11 respectively. The typical resolution of the spectra was 0.2 eV for HSGM and 0.7 eV for DCM beamlines.…”

Section: Methodsmentioning

confidence: 99%

X-ray absorption of Si–C–N thin films: A comparison between crystalline and amorphous phases

Chang

Hsieh

Pong

et al. 1999

Journal of Applied Physics

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X-ray absorption near edge structure ͑XANES͒ spectra of crystalline ͑c͒and amorphous (a)-Si-C-N thin films were measured at the C, N, and Si K edge using the fluorescence and sample drain current modes. A sharp peak similar to the C 1s core exciton in chemical vapor deposition diamond is observed, which can be assigned to the transition from the C 1s to sp 3 hybridized states in c-Si-C-N. The C K edge XANES spectrum of a-Si-C-N contains a relatively large 1s →* peak, implying that carbon atoms in the a-Si-C-N film are bonded largely in graphite-like sp 2 configurations. A shift of the a-Si-C-N * peak towards the lower energy by ϳ0.3 eV relative to that of c-Si-C-N is observed, which can be attributed to a higher degree of disorder-induced localization of excited electrons. Both a-and c-Si-C-N N K-edge XANES spectra resemble that of ␣-Si 3 N 4. The Si K-edge absorption spectra of the Si-C-N thin films indicate a proportional combination of local SiN and Si-C bonds. The increase of the binding energies of excited electrons and the broadening of the spectral features by structural disorder are also observed in the Si K-edge XANES spectrum of the a-Si-C-N film.

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“…3 by a dotted line, is also present at about 4 eV above the L 3 edge, located at 779.4 eV. The XAS spectra, which clearly show no trace of cobalt silicides [ 30 – 31 ], are characteristic of metallic Co [ 32 ]. Such a lineshape has been seen in numerous structures composed of a thin Co layer grown on a metallic substrate [ 1 , 4 , 32 – 34 ] or an insulating support [ 35 ].…”

Section: Resultsmentioning

confidence: 99%

“…Although the shoulder at +4 eV from the L 3 edge can be observed for other Co nanostructures (e.g., an ultrathin 1.25 ML Co film grown on Rh(111) [ 33 ] or a superlattice of 0.35 ML 2D Co nanoparticles on Au(788) [ 4 ]) this feature is more pronounced in the case of our Co nanolines, especially for low Co coverage. It seems reasonable to exclude the formation of a Co silicide or a Co oxide, since in these cases, a more structured absorption spectrum is expected [ 30 , 36 – 37 ]. The XAS signal around this energy may be enhanced by the presence of interface states for Co atoms located at the Co/Si interface as suggested by Pong et al [ 30 ].…”

Section: Resultsmentioning

confidence: 99%

“…It seems reasonable to exclude the formation of a Co silicide or a Co oxide, since in these cases, a more structured absorption spectrum is expected [ 30 , 36 – 37 ]. The XAS signal around this energy may be enhanced by the presence of interface states for Co atoms located at the Co/Si interface as suggested by Pong et al [ 30 ]. For both 1 ML Co and 2 ML Co , the XAS spectra are similar.…”

Section: Resultsmentioning

confidence: 99%

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Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

Michez¹,

Chen²,

Cheynis³

et al. 2015

Beilstein J. Nanotechnol.

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SummaryWe demonstrate the kinetically controlled growth of one-dimensional Co nanomagnets with a high lateral order on a nanopatterned Ag(110) surface. First, self-organized Si nanoribbons are formed upon submonolayer condensation of Si on the anisotropic Ag(110) surface. Depending on the growth temperature, individual or regular arrays (with a pitch of 2 nm) of Si nanoribbons can be grown. Next, the Si/Ag(110) system is used as a novel one-dimensional Si template to guide the growth of Co dimer nanolines on top of the Si nanoribbons, taking advantage of the fact that the thermally activated process of Co diffusion into the Si layer is efficiently hindered at 220 K. Magnetic characterization of the Co nanolines using X-ray magnetic circular dichroism reveals that the first atomic Co layer directly adsorbed onto the Si nanoribbons presents a weak magnetic response. However, the second Co layer exhibits an enhanced magnetization, strongly suggesting a ferromagnetic ordering with an in-plane easy axis of magnetization, which is perpendicular to the Co nanolines.

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X-ray-absorption spectroscopy ofCoSi2

Cited by 11 publications

References 30 publications

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

X-ray absorption of Si–C–N thin films: A comparison between crystalline and amorphous phases

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

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