Author: 焦璐Publisher:
ISBN:
Category : Metallic films
Languages : en
Pages : 0
Book Description
Growth of Transition Metal Dichalcogenide Thin Films by Molecular Beam Epitaxy
Author: 焦璐Growth of Transition Metal Dichalcogenide Thin Films by Molecular Beam Epitaxy
Author: Lu JiaoPublisher: Open Dissertation Press
ISBN: 9781361011959
Category :
Languages : en
Pages :
Book Description
This dissertation, "Growth of Transition Metal Dichalcogenide Thin Films by Molecular Beam Epitaxy" by Lu, Jiao, 焦璐, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Atomically thin transition metal dichalcogenides (TMD) have attracted intensive research interests due to their extraordinary properties and potential applications in electronics and optoelectronics. In this thesis, epitaxial growths of two-dimensional (2D) MoSe2 and WSe2 thin films were carried out in Molecular Beam Epitaxy (MBE). Multiple characterization techniques were employed to investigate thin films' structural, morphological, electronic and optical properties. A series of submonolayer MoSe2 coverage samples have been grown on highly ordered pyrolytic graphite (HOPG) substrate. Growth temperature and post-growth annealing temperature were seen to have obvious impacts on film's morphology and crystal quality. Layer-by-layer growth mode has been identified for the Van der Waals epitaxy of MoSe2 on HOPG. Dense networks of inversion domain boundaries (IDBs) have been observed in as-grown MoSe2 epifilms by scanning tunneling microscopy (STM) and transmission electron microscopy (TEM), and their density can be tuned by changing the MBE conditions. Scanning tunneling spectroscopy (STS) measurements reveal mid-gap electronic states associated with the IDB defects. STS measurements also reveal energy bandgaps of monolayer (ML) and bilayer (BL) MoSe2. ML WSe2 thin films were also grown at varying conditions on HOPG substrates through the Van der Waals epitaxy process and the growth characteristics were found similar to that of MoSe2. However, differences are also noted, particularly about the IDB defects. Contrary to MoSe2, as-grown WSe2 films do not contain the line defects. The reason behind such differences will be discussed. Finally, besides the STM/S studies about the morphological and electronic properties of MBE MoSe2 and WSe2 films, high quality samples have been synthesized on graphene-on-SiC substrate with reduced defect density and well-controlled thicknesses for some ex situ characterizations by photoluminescence and Raman spectroscopy methods. The results will be summarized and discussed in this thesis. Subjects: Molecular beam epitaxy Metallic films
Real Time in Situ Characterization of the Growth of Transition Metal Dichalcogenides Using Synchrotron Radiation
Author: Hugh Joshua BullenPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The isolation of graphene has led to a surge of interest in other 2D materials, primarily layered semiconducting materials that can be utilized in a wide range of applications including but not limited to : optoelectronics, sensing, low-power transistors and flexible electronics. One family of 2D materials that has garnered significant interest is transition metal dichalcogenides. Currently the mechanical exfoliation of these materials is the preferred method for device fabrication. Numerous approaches have been employed to grow crystalline thin films of these materials. Despite the progress that has been made, it is still challenging to achieve growth of defect free, large-area uniform thin films. Before wide-scale application of these materials can be achieved some key issue such as monolayer controllability still need to be further investigated. Here we present our investigation on the thin film growth of 2D transition metal dichalcogenides via metal-organic molecular beam epitaxy (MOMBE), a method not widely used to study the growth of 2D materials, but one that holds promise. This work primarily focuses on the growth of tungsten-based transition metal dichalcogenides and to a lesser extent tungsten-based TMD alloys. We utilize X-ray synchrotron radiation in order to characterize the thin films during growth in situ and in real-time. We also utilize numerous ex situ characterization techniques in this work, such as atomic force microscopy and X-ray photoelectron spectroscopy. We investigate the growth of thin films, specifically the effect of various growth conditions. We consider how the ratio of the incident species affects the growth rate, nucleation and quality of thin films. We also investigated the impact of substrate temperature, the starting substrate and the carrier gas flow rate on the mode of growth, the growth rate, morphology and the composition of the thin films grown by MOMBE. We also employed this approach for the growth of tungsten-based alloys. We find that the carrier gas flow rate and substrate temperature have a significant effect on growth. We also observe that depending on the ratio of incident species, unwanted byproducts may be produced. Finally, using this growth method along with synchrotron characterization techniques, we demonstrate the near layer-by-layer growth of TMD thin films with the expected stoichiometry.
Growth of EuO Thin Films by Molecular Beam Epitaxy
Author: Ross UlbrichtMolecular Beam Epitaxy
Author: Mohamed HeniniPublisher: Elsevier
ISBN: 0128121378
Category : Science
Languages : en
Pages : 790
Book Description
Molecular Beam Epitaxy (MBE): From Research to Mass Production, Second Edition, provides a comprehensive overview of the latest MBE research and applications in epitaxial growth, along with a detailed discussion and 'how to' on processing molecular or atomic beams that occur on the surface of a heated crystalline substrate in a vacuum. The techniques addressed in the book can be deployed wherever precise thin-film devices with enhanced and unique properties for computing, optics or photonics are required. It includes new semiconductor materials, new device structures that are commercially available, and many that are at the advanced research stage. This second edition covers the advances made by MBE, both in research and in the mass production of electronic and optoelectronic devices. Enhancements include new chapters on MBE growth of 2D materials, Si-Ge materials, AIN and GaN materials, and hybrid ferromagnet and semiconductor structures. - Condenses the fundamental science of MBE into a modern reference, speeding up literature review - Discusses new materials, novel applications and new device structures, grounding current commercial applications with modern understanding in industry and research - Includes coverage of MBE as mass production epitaxial technology and how it enhances processing efficiency and throughput for the semiconductor industry and nanostructured semiconductor materials research community
Two-Dimensional Transition-Metal Dichalcogenides
Author: Alexander V. KolobovPublisher: Springer
ISBN: 3319314505
Category : Technology & Engineering
Languages : en
Pages : 545
Book Description
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.
Growth and Applications of Epitaxial Transition Metal Nitride Thin Film Heterostructures
Author: John Gilbert WrightPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Continued improvements in the efficiency and speed of computation and telecommunication requires leveraging the properties of novel materials and materials interfaces. Superconductivity, a phenomenon that until now has not seen widespread application in microelectronic devices, appears poised for extensive implementation in technologies such as single flux quantum (SFQ) digital logic and Josephson junction-based quantum computing. The development of these technologies requires addressing outstanding materials challenges, such as realizing new materials and devices to enable improvements such as increased circuit density for SFQ circuits and low microwave noise Josephson junctions for enhanced coherence time superconducting qubits. Furthermore, while the existing nitride semiconductor materials have enabled new applications in optoelectronics, power electronics, and RF electronics, the ability to integrate these materials in epitaxial structures containing metallic and superconducting thin film materials creates new dimensions in the design space of semiconductor devices, allowing for the creation of novel devices. With these goals in mind, we have pursued the integration of metallic and superconducting transition metal nitrides, such as NbN and TiN, with III-N semiconductors (AlN, GaN, InN). Firstly, we have studied the growth and properties of NbN and TiN films grown by molecular beam epitaxy. We demonstrate that exceptionally high quality epitaxial thin films of NbN can be grown, and that tuning of the growth variables, such as elemental fluxes and substrate temperature, can control the structural phase and superconducting properties of the resultant NbN films. We demonstrate, for the first-time, phase pure beta-Nb2N thin films of the hexagonal crystal structure, and examine their superconducting and structural properties. Additionally, to better understand the electronic properties of both NbN and NbN/III-N interfaces, we examine the electronic interface between GaN and NbN using both Schottky barrier diodes and SX-ARPES, presenting the k-resolved imaging of the electronic states at this technologically interesting materials interface. To enable the realization of hybrid metal-semiconductor nitride devices, a detailed study of the growth of AlN and GaN on NbN is performed. We demonstrate that lattice misfit, surface energy mismatch, and chemical compatibility all present challenges to the realization of these heterostructures. Through the development of new growth strategies, we overcome these issues and demonstrate the growth of high crystal quality epitaxial AlN thin films grown on NbN. Finally, we utilize these films and heterostructures to fabricate several devices. We demonstrate the utilization of ultra-thin epitaxial NbN to fabricate superconducting nanowire single photon detectors (SNSPD). Utilizing the piezoelectric properties of AlN and the metallic properties of NbN, we fabricate epitaxial bulk acoustic wave (BAW) resonators. Finally, using NbN films as superconducting electrodes and an AlN film as a wide band gap semiconductor, we examine the properties of MBE grown NbN/AlN/NbN Josephson junctions.
Growth Kinetics of III-V Semiconductor Thin Films by Molecular Beam Epitaxy with Gas Sources
Author: Bingwen LiangEpitaxial Growth of Complex Metal Oxides
Author: Gertjan KosterPublisher: Woodhead Publishing
ISBN: 0081029462
Category : Science
Languages : en
Pages : 534
Book Description
Epitaxial Growth of Complex Metal Oxides, Second Edition reviews techniques and recent developments in the fabrication quality of complex metal oxides, which are facilitating advances in electronic, magnetic and optical applications. Sections review the key techniques involved in the epitaxial growth of complex metal oxides and explore the effects of strain and stoichiometry on crystal structure and related properties in thin film oxides. Finally, the book concludes by discussing selected examples of important applications of complex metal oxide thin films, including optoelectronics, batteries, spintronics and neuromorphic applications. This new edition has been fully updated, with brand new chapters on topics such as atomic layer deposition, interfaces, STEM-EELs, and the epitaxial growth of multiferroics, ferroelectrics and nanocomposites. - Examines the techniques used in epitaxial thin film growth for complex oxides, including atomic layer deposition, sputtering techniques, molecular beam epitaxy, and chemical solution deposition techniques - Reviews materials design strategies and materials property analysis methods, including the impacts of defects, strain, interfaces and stoichiometry - Describes key applications of epitaxially grown metal oxides, including optoelectronics, batteries, spintronics and neuromorphic applications
Author: Frank Gitmans