Author: Robert MarvelPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 173
Book Description
Physics and Processing of Vanadium Dioxide for Optical Devices
Author: Robert MarvelPublisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 173
Book Description
Vanadium Dioxide for Memory, Oscillators, and Optical Beam Manipulation
Author: Junho JeongPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Vanadium dioxide (VO2), which exhibits insulator-metal transition, has been utilized to demonstrate a non-volatile memory and a tunable metasurface device. To realize these devices, fabrication techniques were developed. Different dry etching recipes were created for making VO2 micro-wires depending on the material crystallinity. In addition, a post-fabrication technique using current injection was developed to create single-crystal VO2 micro-wires from initially poly-crystalline samples. The electrical properties of VO2 become more favorable after this recrystallization process. First, we present a VO2 memory device that demonstrated optically addressable nonvolatile memory at room temperature. The combination of electrical and optical stimuli was used to write memory, and the device state could be read out as voltage oscillations even after several days. This is the first time, to our knowledge, that non-volatile memory is observed in VO2 at room temperature. This observation suggests the presence of a metastable phase in the VO2. Although probing the physical nature of this phase was outside the scope of the thesis, the non-volatile memory effect was studied phenomenologically using VO2 micro-wire devices. Second, we show highly tunable optical transmission in a VO2 optical metasurface. The device consisted of gold (Au) gratings on a VO2 thin film. The gratings simultaneously served to enhance the optical transmission and as resistive heaters. As current was applied through the Au gratings, the localized area of VO2 became metallic due to Joule heating. By switching between extraordinary optical transmission when the VO2 was an insulator to a high absorptive state when the VO2 was metallic, the transmission was tunable by 33 dB/mm. Furthermore, another metasurface device is proposed with simulations displaying reconfigurable beam steering capabilities while using only digital switching of the VO2 elements. With the development of fabrication processes along with the demonstrations of nonvolatile memory and beam manipulation with VO2, this thesis expands the opportunities for VO2 to be used in new types of computing and flat optics devices.
Soviet Physics
Author: Shining Light on the Phase Transitions of Vanadium Dioxide
Author: Tyler J. HuffmanPublisher:
ISBN:
Category : Physics
Languages : en
Pages :
Book Description
The salient feature of the familiar structural transition accompanying the thermally-driven metal-insulator transition in bulk vanadium dioxide (VO2) is a pairing of all the vanadium ions in the monoclinic M¬1 insulating phase. Whether this pairing (unit cell doubling) alone is sufficient to open the energy gap has been the central question of a classic debate which has continued for almost sixty years. Interestingly, there are two less familiar insulating states, monoclinic M2 and triclinic, which are accessible via strain or chemical doping. These phases are noteworthy in that they exhibit distinctly different V-V pairing. With infrared and optical photon spectroscopy, we investigate how the changes in crystal structure affect the electronic structure. We find that the energy gap and optical inter-band transitions are insensitive to changes in the vanadium-vanadium pairing. This result is confirmed by DFT+U and HSE calculations. Hence, our work conclusively establishes that intra-atomic Coulomb repulsion between electrons provides the dominant contribution to the energy gap in all insulating phases of VO2. VO2 is a candidate material for novel technologies, including ultrafast data storage, memristors, photonic switches, smart windows, and transistors which move beyond the limitations of silicon. The attractiveness of correlated materials for technological application is due to their novel properties that can be tuned by external factors such as strain, chemical doping, and applied fields. For advances in fundamental physics and applications, it is imperative that these properties be measured over a wide range of regimes. Towards this end, we study a single domain VO2 crystal with polarized light to characterize the anisotropy of the optical properties. In addition, we study the effects of compressive strain in a VO2 thin film in which we observe remarkable changes in electronic structure and transition temperature. Furthermore, we find evidence that electronic correlations are active in the metallic rutile phase as well. VO2 films exhibit phase coexistence in the vicinity of the metal-insulator transition. Using scanning near-field infrared microscopy, we have studied the patterns of phase coexistence in the same area on repeated heating and cooling cycles. We find that the pattern formation is reproducible each time. This is an unexpected result from the viewpoint of classical nucleation theory that anticipates some degree of randomness. The completely deterministic nature of nucleation and growth of domains in a VO2 film with imperfections is a fundamental finding. This result also holds promise for producing reliable nanoscale VO2 devices.
Transition Metal Oxide Thin Film-Based Chromogenics and Devices
Author: Pandurang AshritPublisher: Elsevier
ISBN: 0081017480
Category : Technology & Engineering
Languages : en
Pages : 378
Book Description
The phase transition and the reversible optical and electrical switching that occur in chromogenic materials under the influence of external forces such as heat, light, and electric field are topics of enormous scientific interest. Transition Metal Oxide Thin Film–Based Chromogenics and Devices discusses experimental and theoretical developments in the field of chromogenics based on the transition metal oxide (TMO) thin films. Understanding the relationship between the switching properties of TMO materials and their nanostructure is of paramount importance in developing efficient chromogenic devices. The tailoring of these switching behaviors is afforded detailed coverage in this book, alongside in-depth discussion of a range of chromogenic materials and devices, including photochromics, thermochromics, and electrochromics. Transition Metal Oxide Thin Film–Based Chromogenics and Devices covers both the theoretical aspects of TMO thin film–based chromogenics and their engineering applications in device construction. Academics and professionals in the fields of materials science and optics will find this book to be a key resource, whether their focus is low-dimension materials, light-materials interactions, or device development. - Enables researchers to keep up with developments in thin film–based chromogenics - Provides detailed coverage of the switching mechanism of the various TMO thin films to assist readers in developing more efficient devices - Offers in-depth discussion of a range of chromogenic materials and devices, including thermochromics, photochromics, and electrochromics
Industrial Applications of Carbon Nanotubes
Author: Huisheng PengPublisher: William Andrew
ISBN: 0323415318
Category : Technology & Engineering
Languages : en
Pages : 510
Book Description
Industrial Applications of Carbon Nanotubes covers the current applications of carbon nanotubes in various industry sectors, from the military to visual display products, and energy harvesting and storage. It also assesses the opportunities and challenges for increased commercialization and manufacturing of carbon nanotubes in the years ahead. Real-life case studies illustrate how carbon nanotubes are used in each industry sector covered, providing a valuable resource for scientists and engineers who are involved and/or interested in carbon nanotubes in both academia and industry. The book serves as a comprehensive guide to the varied uses of carbon nanotubes for specialists in many related fields, including chemistry, physics, biology, and textiles. - Explains how carbon nanotubes can be used to improve the efficiency and performance of industrial products - Includes real-life case studies to illustrate how carbon nanotubes have been successfully employed - Explores how carbon nanotubes could be mass-manufactured in the future, and outlines the challenges that need to be overcome
Protection of Materials and Structures from the Space Environment
Author: Jacob I. KleimanPublisher: Springer Science & Business Media
ISBN: 1402043198
Category : Technology & Engineering
Languages : en
Pages : 456
Book Description
The effects of various space environment factors like atomic oxygen, vacuum ultraviolet radiation, charging, micrometeoroids, meteoroid showers, etc. on materials and structures in various orbits are discussed. In addition the ways to prevent these effects or reduce them through protection by coatings or modification of affected surfaces are considered in the book. The discussions on development of predictive models of material erosion that will allow the materials engineers and designers of future spacecraft to evaluate materials' behaviour is continued from the past meetings.
Studies on Optical Properties and Electron Energy Loss Spectroscopy of Vanadium Dioxide
Author: Mercy ThomasPublisher:
ISBN:
Category : Electron energy loss spectroscopy
Languages : en
Pages : 130
Book Description
The Physics of Ultra-thin Vanadium Dioxide
Author: Nicholas F. QuackenbushPublisher:
ISBN: 9781369135169
Category : Electronic books
Languages : en
Pages : 368
Book Description
Author: