scholarly journals Determination of the embedded electronic states at nanoscale interface via surface-sensitive photoemission spectroscopy

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hui-Qiong Wang ◽  
Jiayi Xu ◽  
Xiaoyuan Lin ◽  
Yaping Li ◽  
Junyong Kang ◽  
...  
Keyword(s):  
Electronic States ◽  
Functional Materials ◽  
Mean Free Path ◽  
Interface States ◽  
Modeling Method ◽  
Quantitative Modeling ◽  
Photoemission Spectroscopy ◽  
Small Scale ◽  
X Ray ◽  
Interface Layers

AbstractThe fabrication of small-scale electronics usually involves the integration of different functional materials. The electronic states at the nanoscale interface plays an important role in the device performance and the exotic interface physics. Photoemission spectroscopy is a powerful technique to probe electronic structures of valence band. However, this is a surface-sensitive technique that is usually considered not suitable for the probing of buried interface states, due to the limitation of electron-mean-free path. This article reviews several approaches that have been used to extend the surface-sensitive techniques to investigate the buried interface states, which include hard X-ray photoemission spectroscopy, resonant soft X-ray angle-resolved photoemission spectroscopy and thickness-dependent photoemission spectroscopy. Especially, a quantitative modeling method is introduced to extract the buried interface states based on the film thickness-dependent photoemission spectra obtained from an integrated experimental system equipped with in-situ growth and photoemission techniques. This quantitative modeling method shall be helpful to further understand the interfacial electronic states between functional materials and determine the interface layers.

scholarly journals Development of a soft X-ray angle-resolved photoemission system applicable to 100 µm crystals

2011 ◽  
Vol 18 (6) ◽  
pp. 879-884 ◽  
Author(s):  
Takayuki Muro ◽  
Yukako Kato ◽  
Tomohiro Matsushita ◽  
Toyohiko Kinoshita ◽  
Yoshio Watanabe ◽  
...  
Keyword(s):  
Electronic States ◽  
Spot Size ◽  
Optical Microscope ◽  
Photoemission Spectroscopy ◽  
Beam Spot ◽  
X Ray ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Clear Band ◽  
Sample Position

A system for angle-resolved photoemission spectroscopy (ARPES) of small single crystals with sizes down to 100 µm has been developed. Soft X-ray synchrotron radiation with a spot size of ∼40 µm × 65 µm at the sample position is used for the excitation. Using this system an ARPES measurement has been performed on a Si crystal of size 120 µm × 100 µm × 80 µm. The crystal was properly oriented on a sample stage by measuring the Laue spots. The crystal was cleavedin situwith a microcleaver at 100 K. The cleaved surface was adjusted to the beam spot using an optical microscope. Consequently, clear band dispersions along the Γ–Xdirection reflecting the bulk electronic states were observed with a photon energy of 879 eV.

scholarly journals Ce 4f electronic states of CeO1−xFxBiS2 studied by soft x-ray photoemission spectroscopy

2017 ◽  
Vol 95 (8) ◽  
Author(s):  
Takanori Wakita ◽  
Kensei Terashima ◽  
Takahiro Hamada ◽  
Hirokazu Fujiwara ◽  
Makoto Minohara ◽  
...  
Keyword(s):  
Electronic States ◽  
Photoemission Spectroscopy ◽  
X Ray

Effect of Si and Ge Interface Layers on the Schottky Barrier Height of Metal Contacts to GaAs

1989 ◽  
Vol 148 ◽  
Author(s):  
J.R. Waldrop ◽  
R.W. Grant
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Photoemission Spectroscopy ◽  
Metal Contacts ◽  
New Approach ◽  
X Ray ◽  
Electrical Methods ◽  
Interface Layers ◽  
P Type

ABSTRACTA new approach for extending the range of the Schottky barrier height ϕB of metal contacts to (100) GaAs is described. Very thin (∼ 10-30Å) heavily n-type and p-type Si or Ge interlayers are found to directly alter the GaAi interface Fermi energy EF. X-ray photoemission spectroscopy is used to determine EF during contact formation and the corresponding ϕB for thick contacts is measured by electrical methods. In an appropriate structure the ϕB range for contacts to n-type GaAs is ∼ 0.25 to 1.0 eV. For p-type GaAs ϕB has been increased to as much as 0.9 eV. This method of ϕBcontrol can be used for both Schottky barrier contact and nonalloyed ohmic contact applications. The results are interpreted in terms of a simple heterojunction model.

Nature of electronic states at the Fermi level of metallicβ−PbO2revealed by hard x-ray photoemission spectroscopy

2007 ◽  
Vol 75 (15) ◽  
Author(s):  
D. J. Payne ◽  
R. G. Egdell ◽  
G. Paolicelli ◽  
F. Offi ◽  
G. Panaccione ◽  
...  
Keyword(s):  
Fermi Level ◽  
Electronic States ◽  
Photoemission Spectroscopy ◽  
X Ray

scholarly journals Strongly Correlated Electronic States in Aqueous Micellar Surfactant

2021 ◽  
Author(s):  
Yuri Mirgorod
Keyword(s):  
Large Scale ◽  
Electronic States ◽  
Micelle Formation ◽  
Thermal Fluctuations ◽  
Small Scale ◽  
Strongly Correlated ◽  
Micellar Solutions ◽  
X Ray ◽  
Cooperative Effects ◽  
White Spots

Abstract Strongly correlated electronic states (SCES), that determine the anomalies of physicochemical properties, are well-known for solid materials at low temperatures. According to the mechanism of manifestation their existence can be assumed in biological cells with white spots, which makes us look into this challenging problem in detail. The paper presents its solution through a study of simple models of micellar solutions of ionic surfactants. The process of micelle formation with accompanying liquid-liquid phase transition makes us pay attention to possible anomalies of properties. Therefore the SCES of water micellar solution has been tested by compenstion and cooperative effects; and by small-angle, wide-angle X-ray, dynamic and chiral scattering of electromagnetic radiation. The solution water is represented by ensembles of small nano systems. Therefore, thermal (cavities for micelles 2-6 nm) and quantum (0.2-0.3 nm) fluctuations of water appear in the zone of concentration of micelle formation. Their energy is approximately equal to the H-bond. Contraction (expansion) of water H-bonds network of due to quantum fluctuations on a small scale correlates with the expansion (contraction) of the in the cavities in the micelles H-bonds network due to thermal fluctuations on a large scale. This phenomenon is caused by SСES.

Electronic states of EuCu2Ge2 and EuCu2Si2 studied by soft x-ray photoemission spectroscopy

2019 ◽  
Vol 100 (3) ◽  
Author(s):  
Ikuto Kawasaki ◽  
Shin-ichi Fujimori ◽  
Yukiharu Takeda ◽  
Hiroshi Yamagami ◽  
Wataru Iha ◽  
...  
Keyword(s):  
Electronic States ◽  
Photoemission Spectroscopy ◽  
X Ray

scholarly journals Investigating valence tautomerism presence in compounds of Co and naphthoquinone

2014 ◽  
Vol 70 (a1) ◽  
pp. C1257-C1257
Author(s):  
Marcos Ribeiro ◽  
Humberto Stumpf ◽  
Carlos Pinheiro
Keyword(s):  
Coordination Compounds ◽  
Metal Ion ◽  
Organic Ligand ◽  
Electronic States ◽  
Functional Materials ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Valence Tautomerism ◽  
X Ray ◽  
Vis Spectroscopy

The search for new functional materials involves the development of bistable molecules exhibiting different electronic states with distinct properties at the ambient condition (temperature, pressure, illumination) of application. Coordination compounds, which present electron transfer between metal ion and an organic ligand associated with a change in electron multiplicity of the metal ion, are named valence tautomers(VT)[1]. The chemical equilibrium between two distinct electronic states in VT can be induced by temperature and pressure change as well as by soft X-ray and light irradiation. Thermodynamic and structural data highlighting the mechanisms of the valence tautomerism interconversion can be found in the literature for materials build up with cobalt and benzoquinones such as the 3,5-di-t-butyl-semiquinonate. However, to the best of our knowledge, there is no example of compounds showing VT build up with cobalt and naphthoquinones. In the present work 2-hydroxy-1,4-naphthoquinone (law) has been used as redox active ligands in the search for new VT compounds with cobalt. Three new coordination compounds of cobalt and 2-hydroxy-1,4-naphthoquinone (law), [Co(law)2(im)2], [Co(law)2(phen)] e [Co(law)2(bpy)] were synthesized and characterized by infrared (IR), UV-vis spectroscopy, electron paramagnetic resonance (EPR) and cyclic voltammetry. The three dimensional structures were determined using single crystal X-ray diffraction techniques. However, within the investigated temperature range neither X-ray diffraction nor EPR data showed the presence of VT in the materials, mainly due to the electrochemical properties of the 2-hydroxy-1,4-naphthoquinone. Nevertheless the structural features of the compounds as well as their supramolecular packing motifs suggest that naphthoquinones can be an alternative for the synthesis of compounds showing valence tautomerism[3].

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