scholarly journals On the Structure of Ultrathin FeO Films on Ag(111)

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 828 ◽  
Author(s):  
Mikołaj Lewandowski ◽  
Tomasz Pabisiak ◽  
Natalia Michalak ◽  
Zygmunt Miłosz ◽  
Višnja Babačić ◽  
...  
Keyword(s):  
Transition Metal ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Lattice Mismatch ◽  
Transition Metal Dichalcogenides ◽  
Chemical Properties ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Free Standing ◽  
Preparation Conditions

Ultrathin transition metal oxide films exhibit unique physical and chemical properties not observed for the corresponding bulk oxides. These properties, originating mainly from the limited thickness and the interaction with the support, make those films similar to other supported 2D materials with bulk counterparts, such as transition metal dichalcogenides. Ultrathin iron oxide (FeO) films, for example, were shown to exhibit unique electronic, catalytic and magnetic properties that depend on the type of the used support. Ag(111) has always been considered a promising substrate for FeO growth, as it has the same surface symmetry, only ~5% lattice mismatch, is considered to be weakly-interacting and relatively resistant to oxidation. The reports on the growth and structure of ultrathin FeO films on Ag(111) are scarce and often contradictory to each other. We attempted to shed more light on this system by growing the films using different preparation procedures and studying their structure using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). We observed the formation of a previously unreported Moiré superstructure with 45 Å periodicity, as well as other reconstructed and reconstruction-free surface species. The experimental results obtained by us and other groups indicate that the structure of FeO films on this particular support critically depends on the films’ preparation conditions. We also performed density functional theory (DFT) calculations on the structure and properties of a conceptual reconstruction-free FeO film on Ag(111). The results indicate that such a film, if successfully grown, should exhibit tunable thickness-dependent properties, being substrate-influenced in the monolayer regime and free-standing-FeO-like when in the bilayer form.

RECENT DEVELOPMENTS IN ALKALI METAL INTERCALATION OF LAYERED TRANSITION METAL DICHALCOGENIDES

2000 ◽  
Vol 14 (13) ◽  
pp. 455-471 ◽  
Author(s):  
H. I. STARNBERG
Keyword(s):  
Transition Metal ◽  
Photoelectron Spectroscopy ◽  
Alkali Metals ◽  
Transition Metal Dichalcogenides ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Recent Developments ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

The modification of layered transition metal dichalcogenides through intercalation is reviewed, with special emphasis on in situ intercalation with alkali metals. Experimental results obtained using photoelectron spectroscopy, low-energy electron diffraction, scanning tunneling microscopy and transmission electron microscopy are presented, and conclusions about the in situ intercalation process and the associated crystallographic and electronic structure changes are presented. It is stressed that various kinds of defects and disorders must be taken into account for a full understanding.

Spatial variation of geometry, binding, and electronic properties in the moiré superstructure of MoS2 on Au(111)

2D Materials ◽  
2022 ◽  
Author(s):  
Caio Silva ◽  
Daniela Dombrowski ◽  
Nicolae Atodiresei ◽  
Wouter Jolie ◽  
Ferdinand Farwick zum Hagen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Spatial Variation ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Lattice Mismatch ◽  
Local Variation ◽  
Scanning Tunneling ◽  
Periodic Pattern ◽  
Tunneling Microscopy ◽  
X Ray

Abstract The lattice mismatch between a monolayer of MoS2 and its Au(111) substrate induces a moiré superstructure. The local variation of the registry between sulfur and gold atoms at the interface leads to a periodic pattern of strongly and weakly interacting regions. In consequence, also the electronic bands show a spatial variation. We use scanning tunneling microscopy and spectroscopy (STM/STS), x-ray photoelectron spectroscopy (XPS) and x-ray standing wave (XSW) for a determination of the geometric and electronic structure. The experimental results are corroborated by density functional theory (DFT). We obtain the geometric structure of the supercell with high precision, identify the fraction of interfacial atoms that are strongly interacting with the substrate, and analyze the variation of the electronic structure in dependence of the location within the moiré unit cell and the nature of the band.

scholarly journals Imaging and identification of point defects in PtTe2

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Kuanysh Zhussupbekov ◽  
Lida Ansari ◽  
John B. McManus ◽  
Ainur Zhussupbekova ◽  
Igor V. Shvets ◽  
...  
Keyword(s):  
Point Defects ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Density Functional Theory Calculations ◽  
Charge Carrier Mobility ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Recombination Rates ◽  
And Performance

AbstractThe properties and performance of two-dimensional (2D) materials can be greatly affected by point defects. PtTe2, a 2D material that belongs to the group 10 transition metal dichalcogenides, is a type-II Dirac semimetal, which has gained a lot of attention recently due to its potential for applications in catalysis, photonics, and spintronics. Here, we provide an experimental and theoretical investigation of point defects on and near the surface of PtTe2. Using scanning tunneling microscopy and scanning tunneling spectroscopy (STS) measurements, in combination with first-principle calculations, we identify and characterize five common surface and subsurface point defects. The influence of these defects on the electronic structure of PtTe2 is explored in detail through grid STS measurements and complementary density functional theory calculations. We believe these findings will be of significance to future efforts to engineer point defects in PtTe2, which is an interesting and enticing approach to tune the charge-carrier mobility and electron–hole recombination rates, as well as the site reactivity for catalysis.

scholarly journals Nanodomain structure of single crystalline nickel oxide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Walls ◽  
A. A. Mazilkin ◽  
B. O. Mukhamedov ◽  
A. Ionov ◽  
I. A. Smirnova ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Domain Structure ◽  
Point Defects ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Gas Sensing ◽  
Density Functional Theory Calculations ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
X Ray

AbstractIn this work we present a comprehensive study of the domain structure of a nickel oxide single crystal grown by floating zone melting and suggest a correlation between point defects and the observed domain structure. The properties and structure of domains dictate the dynamics of resistive switching, water splitting and gas sensing, to name but a few. Investigating the correlation between point defects and domain structure can provide a deeper understanding of their formation and structure, which potentially allows one to tailor domain structure and the dynamics of the aforementioned applications. A range of inhomogeneities are observed by diffraction and microscopy techniques. X-ray and low-energy electron diffraction reveal domains on the submicron- and nanometer-scales, respectively. In turn, these domains are visualised by atomic force and scanning tunneling microscopy (STM), respectively. A comprehensive transmission electron microscopy (TEM) study reveals inhomogeneities ranging from domains of varying size, misorientation of domains, variation of the lattice constant and bending of lattice planes. X-ray photoelectron spectroscopy and electron energy-loss spectroscopy indicate the crystal is Ni deficient. Density functional theory calculations—considering the spatial and electronic disturbance induced by the favourable nickel vacancy—reveal a nanoscale distortion comparable to STM and TEM observations. The different inhomogeneities are understood in terms of the structural relaxation induced by ordering of nickel vacancies, which is predicted to be favourable.

A SCANNING TUNNELING MICROSCOPY STUDY OF MONOLAYER AND BILAYER TRANSITION-METAL DICHALCOGENIDES GROWN BY MOLECULAR-BEAM EPITAXY

2018 ◽  
Vol 25 (Supp01) ◽  
pp. 1841002
Author(s):  
MAOHAI XIE ◽  
JINGLEI CHEN
Keyword(s):  
Molecular Beam Epitaxy ◽  
Transition Metal ◽  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Structural Phase ◽  
Transition Metal Dichalcogenides ◽  
Microscopy Study ◽  
Scanning Tunneling ◽  
Transition Metal Dichalcogenide ◽  
Tunneling Microscopy

This review presents an account of some recent scanning tunneling microscopy and spectroscopy (STM/S) studies of monolayer and bilayer transition-metal dichalcogenide (TMD) films grown by molecular-beam epitaxy (MBE). In addition to some intrinsic properties revealed by STM/S, defects such as inversion domain boundaries and point defects, their properties and induced effects, are presented. More specifically, the quantum confinement and moiré potential effects, charge state transition, quasi-particle interference and structural phase transition as revealed by STM/S are described.

Structural, Optical and Chemical Properties of Zns and Cds Nanoparticles Obtained by an Improved Colloidal Chemistry Synthetic Route.

2001 ◽  
Vol 676 ◽  
Author(s):  
M. Lucia Curri ◽  
Angela Agostiano ◽  
Mario Della Monica ◽  
Gabriella Leo ◽  
Mauro Lomascolo ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Solid Substrate ◽  
Scanning Tunneling ◽  
Cds Nanoparticles ◽  
Synthetic Route ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Vis Spectroscopy ◽  
And Chemical Properties

ABSTRACTIn this work an improved synthetic route that exploits a quaternary water-in-oil microemulsion has been used to obtain nanocrystals of ZnS, CdS and their mixed compounds, - CdxZn1-xS - differing by their size and composition and having high crystalline quality, small dimensions and a quite good size distribution. The opportunity offered by the use of water-in-oil microemulsion to immobilize the nanocrystals onto solid substrate by self-assembling to obtain stable adherent layers has also been exploited.The physical and chemical properties of obtained nanocrystals and layers have been investigated by UV-vis spectroscopy, X-Ray Diffraction X-ray Photoelectron Spectroscopy and Scanning Tunneling Microscopy. The role played by the co-surfactant (pentanol) in controlling nanocrystal size and stability has been discussed.

scholarly journals Uniaxial strain-induced phase transition in the 2D topological semimetal IrTe2

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Christopher W. Nicholson ◽  
Maxime Rumo ◽  
Aki Pulkkinen ◽  
Geoffroy Kremer ◽  
Björn Salzmann ◽  
...  
Keyword(s):  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Gain Control ◽  
Density Functional Theory Calculations ◽  
Uniaxial Strain ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Topological Semimetal ◽  
Topological States ◽  
Metal Dichalcogenides

AbstractStrain is ubiquitous in solid-state materials, but despite its fundamental importance and technological relevance, leveraging externally applied strain to gain control over material properties is still in its infancy. In particular, strain control over the diverse phase transitions and topological states in two-dimensional transition metal dichalcogenides remains an open challenge. Here, we exploit uniaxial strain to stabilize the long-debated structural ground state of the 2D topological semimetal IrTe2, which is hidden in unstrained samples. Combined angle-resolved photoemission spectroscopy and scanning tunneling microscopy data reveal the strain-stabilized phase has a 6 × 1 periodicity and undergoes a Lifshitz transition, granting unprecedented spectroscopic access to previously inaccessible type-II topological Dirac states that dominate the modified inter-layer hopping. Supported by density functional theory calculations, we show that strain induces an Ir to Te charge transfer resulting in strongly weakened inter-layer Te bonds and a reshaped energetic landscape favoring the 6×1 phase. Our results highlight the potential to exploit strain-engineered properties in layered materials, particularly in the context of tuning inter-layer behavior.

LOCAL ELECTRONIC STATES ON TWO-DIMENSIONAL NANOSCALE ISLAND OF Si AND Ge FABRICATED ON Si(111) 7 × 7 SUBSTRATE

2009 ◽  
Vol 08 (06) ◽  
pp. 595-603
Author(s):  
YUKICHI SHIGETA ◽  
RYOTA NEGISHI ◽  
MASAHIKO SUZUKI
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Great Influence ◽  
Energy Difference ◽  
Scanning Tunneling Spectroscopy ◽  
Local Deformation ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Tunneling Microscopy

Nanoscale islands on semiconductor are a strong candidate as building block in nanodevices. In the nanoisland, some local deformation is induced by the surface tension, which has a great influence on the electronic property of the nanoislands. To study the electronic structure of two-dimensional (2D) nanoislands of Si and Ge on the Si(111) 7 × 7 surface, we formed nanoislands of the same size and measured with angle resolved ultraviolet photoelectron spectroscopy (ARUPS), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). We found that the nanoisland shows a characteristic fine structure due to some strain. We also calculated a relation between the strain and electronic state based on the density-functional theory. In the calculation, the dangling-bond state at the strained adatom on the nanoisland (SR state) shifts to lower energy, which has liner dependence with the height of the adatoms. The ARUPS spectrum and the STS show characteristic peaks corresponding to the SR state, whose energy depends on the deformation of the adatom. The height of the adatom on the nanoisland estimated from the energy difference is consistent with a result of the STM measurement. The strain of adatoms can be estimated from the electronic structure.

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