Download or read book Electron Diffraction Study of Transition Metal Dichalcogenides written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phase Transitions in Transition Metal Dichalcogenides Studied by Femtosecond Electron Diffraction written by Kerstin Haupt and published by . This book was released on 2013 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural Dynamics in DCNQI Salts and Transition Metal Dichalcogenides Studied by Electron Diffraction Simulation written by Olufemi Opeyemi Olaoye and published by . This book was released on 2015 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low Energy Electron Diffraction Studies of Transition Metal Oxide Surfaces and Films written by Jian Wang and published by . This book was released on 2005 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of Some Transition Metal Compounds by Electron Microscopy and Neutron Diffraction written by C. Greaves and published by . This book was released on 1973 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Metal Interactions with Transition Metal Dichalcogenides written by Ama Duffie Agyapong and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As field effect transistors (FETs) continue to shrink towards the sub-nanometer regime, interest in two-dimensional transition metal dichalcogenides (2D TMDs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS¬2) grows. Unlike three-dimensional semiconductors, many 2D TMDs remain semiconducting at sub-nanometer thicknesses, which is favorable for the electrostatics of scaled devices. Critical to the successful integration of TMDs in FETs is reducing contact resistance at the metal/semiconductor interface and understanding how metal contacts form on the TMD van der Waals surface. Beyond electronics, there are other fields in which the interactions of metals on TMDs are important, such as catalysis. The goal of this dissertation is to better understand metal/TMD interfaces by examining interfacial reactions, epitaxy of ordered and disordered intermetallic alloys, and the impact of different metal deposition conditions on the structure and doping of TMD monolayers. The first study aims to investigate the reactivity between contact metals (Ti, Al, Cu, Pd, and Au) and 1L WS2. Studies of this buried interface often require destructive techniques, such as using a focused ion beam to access the buried metal/TMD interface for microscopy, which is time-consuming and could potentially modify the interface. The goal of this study was to non-destructively detect interfacial reactions at this interface using Raman spectroscopy as a screening tool to distinguish reactive metals quickly and effectively from non-reactive metals. Our approach involved acquiring Raman spectra from the backside of the metal/WS2 stack through a single-crystal transparent sapphire growth substrate, which allowed us to probe the interface between a coalesced metal film and 1L WS2. The disappearance of the Raman-active phonon modes for WS2 suggested the consumption of WS2 through reactions with the continuous metal film, as observed completely for Ti upon deposition and nearly completely for Al after annealing at and above 100 °C. On the other hand, the persistence of multiple Raman-active phonon modes for WS2 confirms that Au, Cu, and Pd are unreactive with WS2 upon deposition and after cumulatively annealing for 1 h at 100, 200, and 300 °C, even though unreactive metal overlayers could shift some of the peaks in the spectrum. Results matched thermodynamic predictions of metals on bulk WS2. A subsequent study focused on applying criteria for room- and low-temperature quasi-van der Waals epitaxy for elements on MoS2 and WSe2 to the synthesis of highly-oriented single-crystal intermetallic phases on MoS2 growth templates. In addition to thermodynamic stability between the film and substrate, we also considered crystallographic symmetry and atomic mobilities in our selection of intermetallic catalysts to synthesize (PdIn, PdCu, PtAl2, PtCu, PtBi, and PtSn). The phases were directly cosputtered onto exfoliated MoS2 on TEM grids by DC magnetron sputtering with the exception of PtBi where the Pt layer was sputtered, and the Bi layer was evaporated by electron beam evaporation. The Bi/Pt layers were then annealed on a hotplate at 200 °C for 60 min in an ambient environment. We collected plan-view transmission electron microscopy (TEM) images and selected-area electron diffraction (SAED) patterns to determine the phase, crystallinity, and orientation of the intermetallics on MoS2. The resulting PdIn film was highly oriented or textured for as-deposited and annealed conditions with an orientation relationship of PdIn(111)∥MoS_2 (0001); PdIn[11 ̅0]∥MoS_2 [11 ̅00]. We were able to form epitaxial PdCu film at room temperature and after annealing, although they were disordered, obtaining the orientational relationship PdCu(111)∥MoS_2 (0001); PdCu[2 ̅11]∥MoS_2 [11 ̅00]. PtCu was epitaxial at room temperature and after annealing; however, it formed a disordered phase on MoS2 at room temperature with the orientation relationship of PtCu(111)∥MoS_2 (0001);PtCu[2 ̅11]∥MoS_2 [11 ̅00] and an ordered phase on MoS2 after annealing with the orientation relationship of PtCu(0001)∥MoS_2 (0001);PtCu[11 ̅00]∥MoS_2 [11 ̅00]. We observed regions of annealed PtAl2 films in which the (100) PtAl2 plane aligned with the basal plane of MoS2. However, we were unsuccessful in depositing epitaxial PtSn and PtBi on MoS2, possibly due to reaction between S-Sn and incomplete intermixing, respectively. In the final part of this dissertation, we examined the effects of physical vapor deposition of contact metals on 1L MoS2 using the non-destructive backside-illumination Raman spectroscopy method. Metal films (Cu, Pd, Pt, Bi, Sn, and In) were deposited via electron beam (e-beam) evaporation and DC magnetron sputtering at a nominal thickness of 100 nm, except for evaporated Pt (70 nm), which was made thinner due to heat generated during its evaporation. We were able to observe the persistence of the characteristic MoS2 first-order Raman modes after the evaporation of all metals; however, some sputtered metals (Pd, Pt, Sn, and In) showed evidence of damaged 1L MoS2, which resulted in the disappearance of the MoS2 phonon vibrational modes. The degree of damage induced by the sputtering process could be related to the kinetic energies of the atomic species as they arrive at the MoS2 surface. We were able to correlate the disappearance of the first-order Raman modes of the MoS2 beneath the sputtered metals with the cohesive energies of the metals, which correlates with experimentally measured impinging forces of sputtered species from the literature. Our results also indicated that metals with higher cohesive and adsorption energies were more likely to damage monolayer TMDs during sputter deposition. In some cases, we observed the first-order out-of-plane MoS2 vibrational mode redshift or else become two distinct peaks, which tells us about electron doping of MoS2 by metals with modest cohesive and adsorption energies (Bi, In, Sn, and Au). The appearance of the two peaks seems to be linked to metal clusters forming during thin-film deposition and/or bilayer regions on monolayer MoS2, which may result in inhomogeneous doping. The studies presented in this dissertation expand our fundamental understanding of 3D metallic films on 2D semiconductors. They demonstrate and apply a powerful screening tool that provides a non-destructive approach to observing changes at the buried metal/TMD interface. They furthermore contribute to our understanding of the growth of metal and alloy films prepared by physical vapor deposition on transition metal dichalcogenides.

Download or read book Photoelectron Diffraction Studies of Molecular Adsorbates on Transition Metal Surfaces written by Jie Hun Kang and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physica B C written by and published by . This book was released on 1986 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

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.

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for Information and Numerical Data Analysis and Synthesis, (CINDAS) *at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity was transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 19 (thesis year 1974) a total of 10,045 theses titles from 20 Canadian and 209 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. The organization of Volume 19 is identical to that of past years. It consists of theses titles arranged by discipline and by university within each discipline.

Download or read book Transmission Electron Microscopy written by David B. Williams and published by Springer Science & Business Media. This book was released on 2009-07-31 with total page 805 pages. Available in PDF, EPUB and Kindle. Book excerpt: This profusely illustrated text on Transmission Electron Microscopy provides the necessary instructions for successful hands-on application of this versatile materials characterization technique. The new edition also includes an extensive collection of questions for the student, providing approximately 800 self-assessment questions and over 400 questions suitable for homework assignment.

Download or read book International Tables for Crystallography Volume B written by Uri Shmueli and published by Springer Science & Business Media. This book was released on 2008-08-27 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: International Tables for Crystallography are no longer available for purchase from Springer. For further information please contact Wiley Inc. (follow the link on the right hand side of this page). Volume B presents accounts of the numerous aspects of reciprocal space in crystallographic research. After an introductory chapter, Part 1 presents the reader with an account of structure-factor formalisms, an extensive treatment of the theory, algorithms and crystallographic applications of Fourier methods, and fundamental as well as advanced treatments of symmetry in reciprocal space. In Part 2, these general accounts are followed by detailed expositions of crystallographic statistics, the theory of direct methods, Patterson techniques, isomorphous replacement and anomalous scattering, and treatments of the role of electron microscopy and diffraction in crystal structure determination, including applications of direct methods to electron crystallography. Part 3 deals with applications of reciprocal space to molecular geometry and `best'-plane calculations, and contains a treatment of the principles of molecular graphics and modelling and their applications. A convergence-acceleration method of importance in the computation of approximate lattice sums is presented and the part concludes with a discussion of the Ewald method. Part 4 contains treatments of various diffuse-scattering phenomena arising from crystal dynamics, disorder and low dimensionality (liquid crystals), and an exposition of the underlying theories and/or experimental evidence. Polymer crystallography and reciprocal-space images of aperiodic crystals are also treated. Part 5 of the volume contains introductory treatments of the theory of the interaction of radiation with matter (dynamical theory) as applied to X-ray, electron and neutron diffraction techniques. The simplified trigonometric expressions for the structure factors in the 230 three-dimensional space groups, which appeared in Volume I of International Tables for X-ray Crystallography, are now given in Appendix 1.4.3 to Chapter 1.4 of this volume. Volume B is a vital addition to the library of scientists engaged in crystal structure determination, crystallographic computing, crystal physics and other fields of crystallographic research. Graduate students specializing in crystallography will find much material suitable for self-study and a rich source of references to the relevant literature.

Download or read book Synthesis and Characterization of the 2 Dimensional Transition Metal Dichalcogenides written by and published by . This book was released on 2017 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last 50 years, the semiconductor industry has been scaling the silicon transistor to achieve faster devices, lower power consumption, and improve device performance. Transistor gate dimensions have become so small that short channel effects and gate leakage have become a significant problem. To address these issues, performance enhancement techniques such as strained silicon are used to improve mobility, while new high-k gate dielectric materials replace silicon oxide to reduce gate leakage. At some point the fundamental limit of silicon will be reached and the semiconductor industry will need to find an alternate solution. The advent of graphene led to the discovery of other layered materials such as the transition metal dichalcogenides. These materials have a layered structure similar to graphene and therefore possess some of the same qualities, but unlike graphene, these materials possess sizeable bandgaps between 1-2 eV making them useful for digital electronic applications. Since initially discovered, most of the research on these films has been from mechanically exfoliated flakes, which are easily produced due to the weak van der Waals force binding the layers together. For these materials to be considered for use in mainstream semiconductor technology, methods need to be explored to grow these films uniformly over a large area. In this research, atomic layer deposition (ALD) was employed as the growth technique used to produce large area uniform thin films of several different transition metal dichalcogenides. By optimizing the ALD growth parameters, it is possible to grow high quality films a few to several monolayers thick over a large area with good uniformity. This has been demonstrated and verified using several physical analytical tests such as Raman spectroscopy, photoluminescence, x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron spectroscopy, and scanning electron microscopy, which show that these films possess the same qualities as those of the mechanically exfoliated films. Back-gated field effect transistors were created and electrical characterization was performed to determine if ALD grown films possess the same electronic properties as films produced from other methods. The tests revealed that the ALD grown films have high field effect mobility and high current on/off ratios. The WSe2 films also exhibited ambipolar electrical behavior making them a possible candidate for complementary metal-oxide semiconductor (CMOS) technology. Ab-initio density functional theory calculations were performed and compared to experimental properties of MoS2 and WSe2 films, which show that the ALD films grown in this research match theoretical predictions. The transconductance measurements from the WSe2 devices used, matched very well with the theoretical calculations, bridging the gap between experimental data and theoretical predictions. Based upon this research, ALD growth of TMD films proves to be a viable alternative for silicon based digital electronics.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modulated Structures Polytypes and Quasicrystals written by D. Pandey and published by CRC Press. This book was released on 1989 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron Energy Loss Spectroscopy in the Electron Microscope written by R.F. Egerton and published by Springer Science & Business Media. This book was released on 2011-07-29 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the last 30 years, electron energy-loss spectroscopy (EELS) has become a standard analytical technique used in the transmission electron microscope to extract chemical and structural information down to the atomic level. In two previous editions, Electron Energy-Loss Spectroscopy in the Electron Microscope has become the standard reference guide to the instrumentation, physics and procedures involved, and the kind of results obtainable. Within the last few years, the commercial availability of lens-aberration correctors and electron-beam monochromators has further increased the spatial and energy resolution of EELS. This thoroughly updated and revised Third Edition incorporates these new developments, as well as advances in electron-scattering theory, spectral and image processing, and recent applications in fields such as nanotechnology. The appendices now contain a listing of inelastic mean free paths and a description of more than 20 MATLAB programs for calculating EELS data.