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Investigation of Growth, Structural and Electronic Properties of V2O3 Thin Films on Selected Substrates

Investigation of Growth, Structural and Electronic Properties of V2O3 Thin Films on Selected Substrates PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
The present work is devoted to the experimental study of the MI transition in V2O3 thin films, grown on different substrates. The main goal of the work was to develop a technology of growth of V2O3 thin films on substrates with different electrical and structural properties (diamond and LiNbO3), designed for specific applications. The structural and electrical properties of the obtained films were characterized in detail with a special focus on their potential applications. The MIT of V2O3 was investigated by SAW using first directly deposited V2O3 thin film onto a LiNbO3 substrate.

Investigation of Growth, Structural and Electronic Properties of V2O3 Thin Films on Selected Substrates

Investigation of Growth, Structural and Electronic Properties of V2O3 Thin Films on Selected Substrates PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
The present work is devoted to the experimental study of the MI transition in V2O3 thin films, grown on different substrates. The main goal of the work was to develop a technology of growth of V2O3 thin films on substrates with different electrical and structural properties (diamond and LiNbO3), designed for specific applications. The structural and electrical properties of the obtained films were characterized in detail with a special focus on their potential applications. The MIT of V2O3 was investigated by SAW using first directly deposited V2O3 thin film onto a LiNbO3 substrate.

Investigation of Growth, Structural and Electronic Properties of V_1tn2O_1tn3 Thin Films on Selected Substrates

Investigation of Growth, Structural and Electronic Properties of V_1tn2O_1tn3 Thin Films on Selected Substrates PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description


Investigation of Growth, Structural and Electronic Properties of V_1tn2O_1tn3 Thin Films on Selected Substrates

Investigation of Growth, Structural and Electronic Properties of V_1tn2O_1tn3 Thin Films on Selected Substrates PDF Author: Alexei Nateprov
Publisher:
ISBN:
Category :
Languages : en
Pages : 85

Book Description


Structural and Electronic Investigations of In2O3 Nanostructures and Thin Films Grown by Molecular Beam Epitaxy

Structural and Electronic Investigations of In2O3 Nanostructures and Thin Films Grown by Molecular Beam Epitaxy PDF Author: Hongliang Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
Transparent conducting oxides (TCOs) combine optical transparency in the visible region , with a high electrical conductivity. In203 doped with Sn (widely, but somewhat misleadingly, known as indium tin oxide or ITO) is at present the most important TCO, with applications in liquid crystal displays, touch screen displays, organic photovoltaics and other optoelectronic devices. Surprisingly, many of its fundamental properties have been the subject of controversy or have until recently remained unknown, including even the nature and magnitude of the bandgap. The technological importance of the material and the renewed interest in its basic physics prompted the research described in this thesis. This thesis aims (i) to establish conditions for the growth of high-quality 111203 nanostructures and thin films by oxygen plasma assisted molecular beam epitaxy and (ii) to conduct comprehensive investigations on both the surface physics of this material and its structural and electronic properties. It was demonstrated that highly ordered In2O3 nanoislands, nanorods and thin films can be grown epitaxially on (100), (110) and (111) oriented V-stabilized ZrO2 substrates respectively. The mismatch with this substrate is -1.7%, with the epilayer under tensile strain. On the basis of ab initio density functional theory calculations, it was concluded that the striking influence of substrate orientation on the distinctive growth modes was linked to the fact that the surface energy for the (111) surface is much lower than for either polar (l00) or non-polar (l10) surfaces: The growth of In2O3(111) thin films was further explored on Y-ZrO2(l11) substrates by optimizing the growth temperature and film thickness. Very thin In2O3 epilayers (35 nm) grew pseudomorphically under high tensile strain, caused by the 1.7% lattice mismatch with the substrate. The strain was gradually relaxed with increasing film thickness. High-quality films with a low carrier concentration (5.0 x 1017 cm-3) and high mobility (73 cm2V-1s-l) were obtained in the thickest films (420 nm) after strain relaxation The bandgap of the thinnest In2O3 films was around 0.1 eV smaller than that of the bulk material, due to reduction of bonding- antibonding interactions associated with lattice expansion. The high-quality surfaces of the (111) films allowed us to investigate various aspects of the surface structural and electronic properties. The atomic structure of In2O3 (111) surface was determined using a combination of scanning tunnelling microscopy, analysis of intensity/voltage curves in low energy electron diffraction and first-principles ab initio calculations. The (111) termination has an essentially bulk terminated (1 x 1) surface structure, with minor relaxations normal to the surface. Good agreement was found between the experimental surface structure and that derived from ab initio density functional theory calculations. This work emphasises the benefits of a multi-technique approach to determination of surface structure. The electronic properties of In203 (111) surfaces were probed by synchrotron-based photoemission spectroscopy using photons with energies ranging from the ultraviolet (6 eV) to the hard X-ray regime (6000 eV) to excite the spectra. It has been shown that In203 is a highly covalent material, with significant hybridization between 0 and In orbitals in both the valence and the conduction bands. A pronounced electron accumulation layer presents itself at the surfaces of undoped In2O3 films with very low carrier concentrations, which results from the fact the charge neutrality level of In2O3 lies well above the conduction band minimum. The pronounced electron accumulation associated with a downward band bending in the near surface region creates a confining potential well, which causes the electrons in the conduction band become quantized into two subband states, as observed by angle resolved photoemission spectra (ARPES) Fermi surface mapping. The accumulation of high density of electrons near to the surface region was found to shrink the surface band gap through many body interactions. Finally epitaxial growth of In-O3 thin films on a-Al2O3(0001) substrates was investigated. Both the stable body centred cubic phase and the metastable hexagonal corundum In2O3 phase can be stabilized as epitaxial thin films, despite large mismatches with the substrate. The growth mode involves matching small but different integral multiples of lattice planes of the In203 and the substrate in a domain matching epitaxial prowth mode.

Metal-insulator Transition in Epitaxial V2O3 Thin Films

Metal-insulator Transition in Epitaxial V2O3 Thin Films PDF Author: Bamidele S. Allimi
Publisher:
ISBN:
Category :
Languages : en
Pages : 178

Book Description


Studies on Structural and Dielectric Properties of ß-Ga2O3 Thin Films

Studies on Structural and Dielectric Properties of ß-Ga2O3 Thin Films PDF Author: Lee Sang a
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659638916
Category :
Languages : en
Pages : 136

Book Description
In this study we report on structural and electric properties of -Ga2O3 on Si and GaN substrates. Since Ga2O3 has a band-gap of 4.8 eV at room temperature and a dielectric constant of 10.2 14.2, Ga2O3 can be a potential candidate dielectrics for MIS devices. -Ga2O3 has been deposited using various techniques such as radio-frequency sputtering, plasma enhanced atomic layer deposition (PEALD), and pulsed laser deposition (PLD). In particular, epitaxial Ga2O3 thin films grown on n-GaN/Al2O3 substrate by PLD technique have a monoclinc -Ga2O3 phase and peaks were indexed as (-2 0 1) and higher order diffractions. Optical transmittance of the epitaxial -Ga2O3 film was more than 90% from UV to visible spectral regions and the optical band-gap of the -Ga2O3 was calculated to be about 4.8 eV. Moreover, we have fabricated MFIS capacitors using Ga2O3 and Ba0.5Sr0.5TiO3 (BST) thin films on GaN/Al2O3 substrate by pulsed laser deposition. The epitaxial growth, structural analysis, and dielectric properties of the Ga2O3 films and BST thin films will be discussed.

GROWTH OF TRANSITION METAL DIC

GROWTH OF TRANSITION METAL DIC PDF Author: Lu Jiao
Publisher: Open Dissertation Press
ISBN: 9781361011973
Category : Science
Languages : en
Pages : 118

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

Growth and Characterization of Sr2FeMoO6 Thin Films on Ceramic Substrates

Growth and Characterization of Sr2FeMoO6 Thin Films on Ceramic Substrates PDF Author: Santosh Kumar Myana
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
Transition metal oxide heterostructures are known to have shown a wide range of phenomenal properties such as superconductivity, colossal magnetoresistance and multiferroicity. The double perovskite Sr2FeMoO6 (SFMO) is reported to be a ferrimagnetic with high Curie temperature (410 - 450 K), which exhibits an appreciable low field magnetoresistance (LFMR) even at room temperature. Most of the thin film systems are prepared on single crystal substrates such as SrTiO3, LaAlO3, MgO and some limited compositions with few low index orientations available. Here, we used a throughput synthesis technique called Combinatorial Substrate Epitaxy , where we deposit thin films on isostructural polycrystalline substrates, using optimized deposition conditions. We investigate the deposition of SFMO thin films on three different polycrystalline substrates such as Sr2MgWO6 (SMWO), Ba2MgWO6 (BMWO) and Ca2MgWO6 (CMWO), and correlate the structural and electronic properties with the compositions, the strains and nature of defects.

Growth, Structure and Dielectric Properties of SrTiO3 Thin Films on LaAlO3 Substrates

Growth, Structure and Dielectric Properties of SrTiO3 Thin Films on LaAlO3 Substrates PDF Author: Xin Wang
Publisher:
ISBN: 9789178718078
Category :
Languages : en
Pages : 60

Book Description


Lattice Distortion of V2O3 Thin Films During Metal-to-insulator Transition

Lattice Distortion of V2O3 Thin Films During Metal-to-insulator Transition PDF Author: Ziming Shao
Publisher:
ISBN:
Category :
Languages : en
Pages : 55

Book Description
As a prototypical Mott-Hubbard system, bulk vanadium sesquioxide (V2O3), undergoes a first-order Metal-to-Insulator Transition (MIT) from the paramagnetic metallic phase to an antiferromagnetic insulator phase upon cooling to ~160K. Along with MIT, a structural phase transition from rhombohedral to monoclinic structure happens around the same temperature. In the past few decades, the transition temperature of V2O3 has been successfully modified by tens of degrees by introducing lattice strain (through doping, heteroepitaxial growth, etc.). However, how the lattice strain affects the structural distortion and MIT remains elusive to this day. In this work, we studied the lattice distortion of V2O3 thin films heteroepitaxially grown on variously oriented sapphire substrates through X-ray diffraction at Cornell High Energy Synchrotron Source (CHESS). We show that the in-plane biaxial strain drastically affects the intrinsic lattice distortions and the microstrain states in films. Besides, an intermediate interfacial structure was observed in the film grown on (100)-oriented substrate, which is a plausible model for explaining the recent discovery of a memory effect in electrical transport properties of V2O3.