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Book Scanning Tunneling Microscopy and Spectroscopy Investigations Into Transition Metal Substitution in Monolayer Lateral MoSe2 WSe2 Heterojunctions

Download or read book Scanning Tunneling Microscopy and Spectroscopy Investigations Into Transition Metal Substitution in Monolayer Lateral MoSe2 WSe2 Heterojunctions written by 李星燁 and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Probing Transition Metal Dichalcogenide Monolayers and Heterostructures by Optical Spectroscopy and Scanning Tunneling Spectroscopy

Download or read book Probing Transition Metal Dichalcogenide Monolayers and Heterostructures by Optical Spectroscopy and Scanning Tunneling Spectroscopy written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We then compare our results with the exciton lifetime in MoS2/WS2 and MoSe2/WSe2 heterostructures. In TMDC/TMDC heterostructures, the decrease in exciton lifetime is twice that in WS2/graphene heterostructures and due predominantly to charge transfer between the layers. Finally, we probe the band alignment in MoS2/WS2 heterostructures using scanning tunneling microscopy (STM) and spectroscopy (STS).We confirm the monolayer band gaps and the predicted type II band alignment in the heterostructure. Drawing from all the research presented, we arrive at a favorable conclusion about the viability of TMDC based devices.

Book Two Dimensional Transition Metal Dichalcogenides

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Narayanasamy Sabari Arul and published by Springer. This book was released on 2019-07-30 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents advanced synthesis techniques adopted to fabricate two-dimensional (2D) transition metal dichalcogenides (TMDs) materials with its enhanced properties towards their utilization in various applications such as, energy storage devices, photovoltaics, electrocatalysis, electronic devices, photocatalysts, sensing and biomedical applications. It provides detailed coverage on everything from the synthesis and properties to the applications and future prospects of research in 2D TMD nanomaterials.

Book Scanning Tunneling Microscopy Investigations of Metal Dichalcogenide Materials

Download or read book Scanning Tunneling Microscopy Investigations of Metal Dichalcogenide Materials written by and published by . This book was released on 1993 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have been used to characterize the atomic level structure of electronic properties, reactivity and wear of metal dichalcogenide materials that are or have potential as solid state lubricants. Single crystals Of MoS2, Ni(x)Mo(l-x) S2, MoS(2-x)Se(x) and MoS(2-x)Te(x) have been prepared to determine how chemical modifications affect the local structure and electronic properties of this lubricant. STM images of Ni-doped MoS2 show localized electronic states due to the Ni atoms, while images of Se- and Te-doped materials indicate that anion substitution is electronically delocalized. AFM studies of Te-doped MoS2 show, however, that the tellurium dopants form atomic scale structural protrusions that may reduce sliding friction. AFM has also been used to characterize nanometer scale wear and oxidation on MoS2 and NbSe2 surfaces. In atmosphere at room-temperature AFM studies showed that NbSe2 wears approximately three times faster than MoS2. Furthermore, oxidation studies demonstrated that NbSe2 was significantly more reactive than MoS2 with molecular oxygen. These results indicate that the intrinsic stability of the MoS2 surface make it an effective lubricant, AFM was also used to elucidate the growth of MoO3 on the surface Of MoS2 during oxidation, and to study wear properties of these MoO3 crystallites. The AFM tip was used to define lines with 10 nm resolution in MoO3 and to manipulate distinct MoO3 structures on the MoS2 surface. In addition, metal- substitution in TaS2 has been studied systematically using STM and theoretical methods.

Book Internal Photoemission Spectroscopy

Download or read book Internal Photoemission Spectroscopy written by Valeri V. Afanas'ev and published by Elsevier. This book was released on 2014-02-22 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Internal Photoemission Spectroscopy thoroughly updates this vital, practical guide to internal photoemission (IPE) phenomena and measurements. The book's discussion of fundamental physical and technical aspects of IPE spectroscopic applications is supplemented by an extended overview of recent experimental results in swiftly advancing research fields. These include the development of insulating materials for advanced SiMOS technology, metal gate materials, development of heterostructures based on high-mobility semiconductors, and more. Recent results concerning the band structure of important interfaces in novel materials are covered as well. Internal photoemission involves the physics of charge carrier photoemission from one solid to another, and different spectroscopic applications of this phenomenon to solid state heterojunctions. This technique complements conventional external photoemission spectroscopy by analyzing interfaces separated from the sample surface by a layer of a different solid or liquid. Internal photoemission provides the most straightforward, reliable information regarding the energy spectrum of electron states at interfaces. At the same time, the method enables the analysis of heterostructures relevant to modern micro- and nano-electronic devices as well as new materials involved in their design and fabrication. - First complete model description of the internal photoemission phenomena - Overview of the most reliable energy barrier determination procedures and trap characterization methods - Overview of the most recent results on band structure of high-permittivity insulating materials and their interfaces with semiconductors and metals

Book Two Dimensional Transition Metal Dichalcogenides

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Alexander V. Kolobov and published by Springer. This book was released on 2016-07-26 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the current status of theoretical and experimental progress in 2 dimensional graphene-like monolayers and few-layers of transition metal dichalcogenides (TMDCs). Semiconducting monolayer TMDCs, due to the presence of a direct gap, significantly extend the potential of low-dimensional nanomaterials for applications in nanoelectronics and nano-optoelectronics as well as flexible nano-electronics with unprecedented possibilities to control the gap by external stimuli. Strong quantum confinement results in extremely high exciton binding energies which forms an interesting platform for both fundamental studies and device applications. Breaking of spatial inversion symmetry in monolayers results in strong spin-valley coupling potentially leading to their use in valleytronics. Starting with the basic chemistry of transition metals, the reader is introduced to the rich field of transition metal dichalcogenides. After a chapter on three dimensional crystals and a description of top-down and bottom-up fabrication methods of few-layer and single layer structures, the fascinating world of two-dimensional TMDCs structures is presented with their unique atomic, electronic, and magnetic properties. The book covers in detail particular features associated with decreased dimensionality such as stability and phase-transitions in monolayers, the appearance of a direct gap, large binding energy of 2D excitons and trions and their dynamics, Raman scattering associated with decreased dimensionality, extraordinarily strong light-matter interaction, layer-dependent photoluminescence properties, new physics associated with the destruction of the spatial inversion symmetry of the bulk phase, spin-orbit and spin-valley couplings. The book concludes with chapters on engineered heterostructures and device applications such as a monolayer MoS2 transistor. Considering the explosive interest in physics and applications of two-dimensional materials, this book is a valuable source of information for material scientists and engineers working in the field as well as for the graduate students majoring in materials science.

Book Scanning Probe Microscopy Studies of an Electroactive Self assembling Monolayer and Potential Dependent Adhesion of Ferrocenyl Redox Films

Download or read book Scanning Probe Microscopy Studies of an Electroactive Self assembling Monolayer and Potential Dependent Adhesion of Ferrocenyl Redox Films written by James Edgar Hudson and published by . This book was released on 1996 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scanning Tunneling Microscopy Investigation of the Vanadium Dioxide Surface and Its Related Metal insulator Transition MIT

Download or read book Scanning Tunneling Microscopy Investigation of the Vanadium Dioxide Surface and Its Related Metal insulator Transition MIT written by Wenjing Yin and published by . This book was released on 2009 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Engineering of Mixed Phase Transition Metal Dichalcogenide Materials

Download or read book Engineering of Mixed Phase Transition Metal Dichalcogenide Materials written by William R. Scougale and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of smaller, and new computation devices continues to drive interest in the fundamental physical sciences and their possible applications to improved computation capability. With the infancy of quantum computing, much research has been devoted to developing greater noise tolerance in qubit technologies. In addition, other avenues for improvement remain for classical computing, particularly with scaling electronic systems from 3D to 2D. Recently, transition metal dichalcogenide materials have drawn interest due to their extensive variety of material properties, stable chemical state, and comparably easy exfoliation. These materials are routinely reduced to 2D sheets and can be stacked to produce devices. Unanticipated physical phenomena have been observed in such stacked layers, as seen with magic angle graphene. These properties are driven by moiré interactions between the layers, which can vary continuously with parameters such as lattice size and shape, twist angle, and strain. This produces an incredible number of possible combinations of materials and moiré patterns, all of which could produce useful properties. In this work, a mixed phase growth approach to local nanoscopic measurements is detailed. In particular, it is found that for tungsten disulfide these mixed phase crystals are ideal for examining a broad variety of phase mixing and moiré interactions. Finally, a few physical systems are examined in detail including a 2M-2H vertical heterostructure moiré pattern, the appearance of stripe phase moiré patterning not predicted by rigid modeling, and finally the realization of a possible Kondo Lattice on a 2M-2M-2H moiré region.

Book Scanning Tunneling Microscopy and Spectroscopy of Metal Organic Complexes

Download or read book Scanning Tunneling Microscopy and Spectroscopy of Metal Organic Complexes written by Kezilebieke Shawulienu and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the bottom up approach of today's nanoscience, the supramolecular assembly of metal atoms and molecules on surfaces is leading to functional compounds, relevant to many applications in optoelectronics, magnetism, and catalysis. It has been found that in some cases high magnetic spin states and strong magnetic anisotropy appear as a result of electron transfer between ligands, surface and metal atom. The focus of this thesis lies on the self assembling of 1,2,4,5-Tetracyanobenzene (TCNB) and Fe-TCNB coordination nanostructures on the Au(111) surface. The structural formation is directed by the non covalent interactions. Scanning tunneling spectroscopy (STS) reveal that the TCNB molecules are physisorbed on Au(111) surface. By detail analysis of the dI/dV spectra above the TCNB monolayer on the Au(111) surface, we found that the TCNB molecules on Au(111) shows a negligible charge transfer with Au(111) substrate and a small adsorption energy of 0.5 eV per TCNB molecules. STS measurement provide a HOMO-LUMO gap of 3 eV in agreement with DFT calculations. By controlling the fabrication parameters, surface coordination nanostructures with different chemical composition or molecular packing have been synthesized. The electronic properties have been characterized by the local dI/dV analysis of the metal centers at different steps of a Fe-(TCNB)x (x=4, 2) complexes formation. At low temperature deposition, first form an ordered metastable intermediate. STM data yield the bond angle between the Fe-N-C is 120°. The scanning tunneling spectroscopy reveal that Fe atoms and the TCNB molecules keep their identity while the Fe atoms localize the surface-state electrons similar to what they do on the bare Au(111) surface. This result indicates that the TCNB molecules are virtually in the same electronic state as before the Fe adsorption. The situations are different when the deposition performance at room temperature. When the temperature is changed, to room temperature, the original entities transform into the Fe(TCNB)4 monomer complexes with 180° Fe-N-C bond angles. The STS above the Fe(TCNB)4 complex strongly suggest that the coordination bond had been formed between the Fe atom and the TCNB ligands. DFT calculations support the conclusions and drawn from experimental studies and assist the interpretations of experiment. Further structural complexation is achieved by the synthesis of Fe(TCNB)2 network. The network has a square structure with a regular separation of the magnetic Fe atoms in the network. The electronic information is gathered from the spectroscopic labeling of FePc to identify some of the resonances of the Fe(TCNB)2 network. There are similar features are found in the dI/dV spectra above the Fe atoms and ligand in both system, indicating that the Fe somehow feels a similar environment from the TCNB ligands in the network and in the FePc molecules. Further analysis of this feature have been disused by means of metal-ligand bond formation.

Book Terahertz Scanning Tunneling Microscopy of Metal and Superconductor Surfaces

Download or read book Terahertz Scanning Tunneling Microscopy of Metal and Superconductor Surfaces written by Howe Simpson and published by . This book was released on 2021 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The advent of the terahertz scanning tunneling microscope (THz-STM) brings with it a new method of observing and characterizing the ultrafast dynamics of materials. The sub-nanometer spatial resolution of an ultra-high vacuum scanning tunneling microscope (UHV-STM) coupled with the sub-picosecond time resolution from a terahertz (THz) pulse allows for ultrafast measurements of surface dynamics across varying surface features down to the atomic scale. This thesis explores STM and THz-STM of metal and superconductor surfaces. High critical temperature superconductivity has been an area Bi2Sr2CaCu2O8 is an excellent candidate to study the superconductive process due to its high critical temperature of 95 K and ease of cleaving. STM and scanning tunneling spectroscopy measurements on the high-temperature superconductor Bi2Sr2CaCu2O8 are performed at 100 K and 55 K. STM and STS measurements were also performed on the surface of flat Au(111). Given gold's versatility as a substrate for many STM measurements, it is important to ensure that the STM system used in this study can replicate results that coincide with many other studies done on the surface of gold. The characteristics of the substrate such as flatness and cleanliness prior to deposition of other materials were investigated. The herringbone surface reconstruction of Au(111) was imaged and the topography was analysed with good agreement compared to other studies. Finally, optical-pump/THz-STM-probe measurements are performed on a silver-coated gold surface. These measurements, with tip-sample distances outside of the typical tunneling regime of the THz-STM, use photo-excited electrons from an optical pump beam to tunnel between the sample and tip. A THz pulse is then focused onto the junction between the sample and tip. The results show an interesting behaviour in the regime where the pump beam is not focused on the junction but elsewhere on the surface of the sample. These preliminary results may help gain a better understanding of the photoemission-based THz waveform measurements, as well as demonstrate a new use of the THz-STM for propagation dynamics of surface excitations.

Book 2D Metal Carbides and Nitrides MXenes

Download or read book 2D Metal Carbides and Nitrides MXenes written by Babak Anasori and published by Springer Nature. This book was released on 2019-10-30 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the rapidly expanding field of two-dimensional (2D) transition metal carbides and nitrides (MXenes). It covers fundamental knowledge on synthesis, structure, and properties of these new materials, and a description of their processing, scale-up and emerging applications. The ways in which the quickly expanding family of MXenes can outperform other novel nanomaterials in a variety of applications, spanning from energy storage and conversion to electronics; from water science to transportation; and in defense and medical applications, are discussed in detail.