Download or read book Growth and Characterization of Sr2FeMoO6 Thin Films on Ceramic Substrates written by Santosh Kumar Myana and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Growth and Characterization of Novel Thin Films for Microelectronic Applications written by Mahmoud Vahidi and published by . This book was released on 2013 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: I studied the properties of novel Co2FeAl0.5Si0.5 (CFAS), ZnGeAs2, and FeS2 (pyrite) thin films for microelectronic applications ranging from spintronic to photovoltaic. CFAS is a half metal with theoretical spin polarization of 100%. I investigated its potential as a spin injector, for spintronic applications, by studying the critical steps involved in the injection of spin polarized electron populations from tunnel junctions containing CFAS electrodes. Epitaxial CFAS thin films with L21 structure and saturation magnetizations of over 1200 emu/cm3 were produced by optimization of the sputtering growth conditions. Point contact Andreev reflection measurements show that the spin polarization at the CFAS electrode surface exceeds 70%. Analyses of the electrical properties of tunnel junctions with a superconducting Pb counter-electrode indicate that transport through native Al oxide barriers is mostly from direct tunneling, while that through the native CFAS oxide barriers is not. ZnGeAs2 is a semiconductor comprised of only inexpensive and earth-abundant elements. The electronic structure and defect properties are similar in many ways to GaAs. Thus, in theory, efficient solar cells could be made with ZnGeAs2 if similar quality material to that of GaAs could be produced. To understand the thermochemistry and determine the rate limiting steps of ZnGeAs2 thin-film synthesis, the (a) thermal decomposition rate and (b) elemental composition and deposition rate of films were measured. It is concluded that the ZnGeAs2 thin film synthesis is a metastable process with an activation energy of 1.08±0.05 eV for the kinetically-limited decomposition rate and an evaporation coefficient of ~10-3. The thermochemical analysis presented here can be used to predict optimal conditions of ZnGeAs2 physical vapor deposition and thermal processing. Pyrite (FeS2) is another semiconductor that has tremendous potential for use in photovoltaic applications if high quality materials could be made. Here, I present the layer-by-layer growth of single-phase pyrite thin-films on heated substrates using sequential evaporation of Fe under high-vacuum followed by sulfidation at S pressures between 1 mTorr and 1 Torr. High-resolution transmission electron microscopy reveals high-quality, defect-free pyrite grains were produces by this method. It is demonstrated that epitaxial pyrite layer was produced on natural pyrite substrates with this method.
Download or read book Exploration and Engineering of Physical Properties in High quality Sr2CrReO6 Epitaxial Films written by Jeremy M. Lucy and published by . This book was released on 2015 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: Double perovskites have proven to be highly interesting materials, particularly in the past two decades, with many materials in this family exhibiting strong correlations. These materials are some of many novel complex oxides with potential spintronics application. Sr2CrReO6, in particular, is a double perovskite with one of the highest Curie temperatures of its class (> 620 K in bulk and ~510-600 K in thin films), as well as high spin polarization, ferrimagnetic behavior, and semiconducting properties. This dissertation covers recent work in exploring and tuning physical properties in epitaxial films of Sr2CrReO6. It starts by providing a background for the field of spintronics and double perovskites, bulk and thin film synthesis of Sr2CrReO6, and standard and specialized characterization techniques utilized in both university and national laboratories, and then provides reports of work on Sr2CrReO6 epitaxial films. Examples of exploration and engineering of properties of Sr2CrReO6 include: (1) tuning of electrical resistivity, such as at T = 7 K by a factor of 18,000%, via control of oxygen partial pressure during film growth; (2) enhancement of interfacial double perovskite ordering, demonstrated with high-angle annular dark-field scanning transmission electron microscopy, via the use of double perovskite buffer layer substrates; (3) measurement of magnetization suppression near film/substrate interfaces via polarized neutron reflectometry, which reveals a reduction of thickness (from 5.6 nm to 3.6 nm) of the magnetically suppressed interface region due to buffer layer enhancement; (4) strain tunability of atomic spin and orbital moments of Cr, Re, and O atoms probed with x-ray magnetic circular dichroism, which demonstrates ferrimagnetic behavior and reveals important magnetic contributions of the oxygen sites (~0.02 μB/site); (5) strain tunability of large magnetocrystalline anisotropy via applied epitaxial strain, revealing anisotropy fields of up to 10s of tesla; and (6) depth-resolved synchrotron x-ray studies of correlated magnetic and structural relaxation in a thick relaxing film. The utilized techniques and demonstrated results for Sr2CrReO6 will hopefully benefit researchers of complex oxide materials and perhaps stimulate further work on this and other related materials.
Download or read book Growth and Characterization of Epitaxial Oxide Thin Films written by Ashish Garg and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Epitaxial oxide thin films are used in many technologically important device applications. This work deals with the deposition and characterization of epitaxial WO3 and SrBi2Ta2O9 (SBT) thin films on single crystal oxide substrates. WO3 thin films were chosen as a subject of study because of recent findings of superconductivity at surfaces and twin boundaries in the bulk form of this oxide. Highly epitaxial thin films would be desirable in order to be able to create a device within a film without patterning it, by locally creating superconducting regions (e.g. twins) within an otherwise defect free film by reducing or doping the film with Na. Films were deposited by reactive magnetron sputtering at various temperatures on single crystal SrTiO3 (100) and R-sapphire substrates. X-ray diffraction studies showed that the optimised films were highly (001) oriented, quality of epitaxy improving with decreasing deposition temperature. AFM studies revealed columnar growth of these films. Films were heat treated with Na vapour in order to reduce or dope them with Na. Low temperature measurements of the reduced films did not show existence of any superconductivity. SBT is a ferroelectric oxide and its thin films are attractive candidates for non-volatile ferroelectric random access memory (FRAM) applications. High structural anisotropy leads to a high degree of anisotropy in its ferroelectric properties which makes it essential to study epitaxial SBT films of different orientations. In this study, SBT films of different orientations were deposited on different single crystal substrates by pulsed laser ablation. Highly epitaxial c-axis oriented and smooth SBT films were deposited on SrTiO3 (100) substrates. AFM studies revealed the growth of these films by 3-D Stranski-Krastanov mode. However, these films did not exhibit any ferroelectric activity. Highly epitaxial (116)-oriented films were deposited on SrTiO3 (110) substrates. These films were also very smooth with root mean square (RMS) roughness of 15-20 Å. Films deposited on TiO2 (110) were partially a-/b-axis oriented and showed the formation of c-axis oriented SBT and many impurities. Completely a-/b-axis oriented SBT films were deposited on LaSrAlO4 (110) substrates. Films deposited at non-optimal growth temperatures showed the formation of many impurities. Attempts were also made towards depositing Sr2RuO4 films on LaSrAlO4 (110) substrates, which can act as a bottom electrode for ferroelectric SBT films.
Download or read book Growth Characterization and Measurement of Epitaxial Sr2RuO4 Thin Films written by Jing Cao and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unlocking the Potential of Half metallic Sr2FeMoO6 Thin Films Through Controlled Stoichiometry and Double Perovskite Ordering written by Adam Joseph Hauser and published by . This book was released on 2010 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Sr2FeMoO6 is the most studied half-metallic double perovskite with the potential for room-temperature magnetoelectronic applications due to its Curie temperature above 400 K. Despite its promise, researchers have not yet succeeded in growing films of sufficient quality to realize its potential. By identifying and controlling critical factors that complicate attempts to grow thin films of Sr2FeMoO6, we have overcome the obstacles of non-stoichiometry, impurity phase formation and poor double perovskite ordering, all of which must be overcome to achieve half-metallicity. This dissertation reports an in-depth investigation that addresses several critical issues about the deposition of Sr2FeMoO6 epitaxial films using off-axis ultrahigh vacuum sputtering. High quality Sr2FeMoO6 films have been grown by off-axis ultrahigh vacuum DC magnetron sputtering, and characterized by a wide variety of techniques. We have discovered that sputtering gas pressure plays a dominant role in the stoichiometry and phase formation of Sr2FeMoO6 films. Film stoichiometry was found via Rutherford backscattering spectroscopy (RBS) and electron dispersive x-ray (EDX) spectroscopy to be both position dependent and pressure dependent in off-axis magnetron sputtering, changing from a Mo:Fe ratio of 1.43:1 at PTot = 70 mTorr to 1.12:1 at PTot = 6.7 mTorr. Our Sr2FeMoO6 films exhibit a combination of desired properties expected for its half-metallicity. X-ray-diffractometry (XRD) shows the films to be epitaxial, pure-phase, and well ordered by Reitveld refinement ([Xi]= 85.4%). High angle annular dark field scanning transmission microscopy (HAADF STEM) was performed to give the first direct observation of double perovskite ordering in a film, as well as a low defect level. Magnetic characterization was done via vibrating sample magnetometry (VSM) and superconducting quantum interference device (SQUID) magnetometry to find a saturation magnetization of 2.6 uB per formula unit at T = 5 K and a Curie temperature TC of 380 K, roughly in line with expectation for the film stoichiometry and ordering level. This dissertation also reports the first known report of distinct magnetic shape anisotropy, suggesting a high quality film with long-range magnetic ordering. The Sr2FeMoO6 films with these attributes will provide the material base for magnetoelectronic applications that will eventually achieve its half-metallic potential.
Download or read book Growth and Characterization of Undoped and Doped Silicon Thin Films Using Supersonic Molecular Jets written by Rajeev Malik and published by . This book was released on 1996 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Growth and Characterization of SrTio3 Based Thin Films written by Roman Rechter and published by . This book was released on 2011 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microstructural and Electrical Characterization of Barium Strontium Titanate Based Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition written by Costas G. Fountzoulas and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ferroelectrics are multicomponent materials with a wealth of interesting and useful properties, such as piezoelectricity. The dielectric constant of the BSTO ferroelectrics can be changed by applying an electric field. Variable dielectric constant results in a change in phase velocity in the device allowing it to be tuned in real time for a particular application. The microstructure of the film influences the electronic properties which in turn influences the performance of the film. Ba(0.6)Sr(0.4)Ti(1-y)(A(3+), B(5+))(y)O3 thin films, of nominal thickness of 0.65 micrometer, were synthesized initially at substrate temperatures of 400 deg C, and subsequently annealed to 750 deg C, on LaAlO3 (100) substrates, previously coated with LaSrCoO conductive buffer layer, using the pulsed laser deposition technique. The microstructural and physical characteristics of the post-annealed thin films have been studied using x-ray diffraction, scanning electron microscopy, and nano indentation and are reported. Results of capacitance measurements are used to obtain dielectric constant and tunability in the paraelectric (T>Tc) regime.
Download or read book The Growth and Characterization of II VI Semiconductor Thin Films written by A. M. Patterson and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Epitaxial Growth and Characterisation of Topological Semimetal Thin Films written by Thomas Joseph Rehaag and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Growth Structural and Electronic Properties of V 1tn2O 1tn3 Thin Films on Selected Substrates written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Growth and Thermal Behaviors of Thin Films for the Advanced Gate Stack Grown by Chemical Vapor Deposition written by Taek Soo Jeon and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Growth and Characterization of Magnetoelectric and Multiferroic Oxide Thin Films written by Jinxing Zhang and published by . This book was released on 2009 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heteroepitaxial Growth of Metal Thin Films on Chiral and Achiral Ceramic Substrates written by Andrew J. Francis and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Growth and Characterization of II IV Semiconductor Thin Films written by Anthony Michael Patterson and published by . This book was released on 1984 with total page 1681 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Thin Films of Novel Functionalised 2 5 dithienylpyrrole Derivatives on Oxide Substrates written by Sonia Oberoi and published by . This book was released on 2005 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
