Download or read book Transition Metal Doped Zinc Oxide as Diluted Magnetic Semiconductor written by Zheng Zuo and published by . This book was released on 2013 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal doped ZnO has been proposed to be a Diluted Magnetic Semiconductor with room temperature ferromagnetism. High quality Mn doped ZnO was grown on R-sapphire substrate. Results support intrinsic ferromagnetism, while [Mu]B/ion number was found to be larger than maximum permitted by Hund's law. Saturation strength and coercivity field was found to be manipulated by varying Mn doping concentration. Mn/Ag co-doping was found to alter saturation strength and coercivity field as well. Ag was investigated as substitution dopant to achieve high quality p-type ZnO. With optimization of growth parameters, phase segregation was suppressed and p-type was observed. Besides being p-type, Ag doped ZnO was found to exhibit room temperature ferromagnetism. This is the first high quality demonstration of Ag doped ZnO as DMS.

Download or read book DEFECTS AND FERROMAGNETISM IN TRANSITION METAL DOPED ZINC OXIDE written by Sunil Thapa and published by . This book was released on 2016 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal doped zinc oxide has been studied recently due to its potential application in spintronic devices. The magnetic semiconductor, often called Diluted Magnetic Semiconductors (DMS), has the ability to incorporate both charge and spin into a single formalism. Despite a large number of studies on ferromagnetism in ZnO based DMS and the realization of its room temperature ferromagnetism, there is still a debate about the origin of the ferromagnetism. In this work, the synthesis and characterization of transition metal doped zinc oxide have been carried out. The sol-gel method was used to synthesize thin films, and they were subsequently annealed in air. Characterization of doped zinc oxide films was carried out using the UV-visible range spectrometer, scanning electron microscopy, superconducting quantum interference device (SQUID), x-ray diffraction(XRD) and positron annihilation spectroscopy. Hysteresis loops were obtained for copper and manganese doped zinc oxide, but a reversed hysteresis loop was observed for 2% Al 3% Co doped zinc oxide. The reversed hysteresis loop has been explained using a two-layer model.

Download or read book Study of Diluted Magnetic Semiconductors the Case of Transition Metal Doped ZnO written by Zlatko Micković and published by . This book was released on 2010 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Novel Diluted Magnetic Semiconductor Materials based on Zinc Oxide written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary aim of this work was to develop a ZnO based diluted magnetic semiconductor (DMS) materials system which displays ferromagnetism above room temperature and to understand the origin of long-range ferromagnetic ordering in these systems. Recent developments in the field of spintronics (spin based electronics) have led to an extensive search for materials in which semiconducting properties can be integrated with magnetic properties to realize the objective of successful fabrication of spin-based devices. For these devices we require a high efficiency of spin current injection at room temperature. Diluted magnetic semiconductors (DMS) can serve this role, but they should not only display room temperature ferromagnetism (RTFM) but also be capable of generating spin polarized carriers. Transition metal doped ZnO has proved to be a potential candidate as a DMS showing RTFM. The origin of ferromagnetic ordering in ZnO is still under debate. However, the presence of magnetic secondary phases, composition fluctuations and nanoclusters could also explain the observation of ferromagnetism in the DMS samples. This encouraged us to investigate Cu-doped(+ ư spin in the 2+ valence state) ZnO system as a probable candidate exhibiting RTFM because neither metallic Cu nor its oxides (Cu2O or CuO) are ferromagnetic. The role of defects and free carriers on the ferromagnetic ordering of Cu-doped ZnO thin films was studied to ascertain the origin of ferromagnetism in this system. A novel non-equilibrium Pulsed Laser Deposition technique has been used to grow high quality epitaxial thin films of Cu:ZnO and (Co, Cu):ZnO on c-plane Sapphire by domain matching epitxay. Both the systems showed ferromagnetic ordering above 300K but Cu ions showed a much stronger ferromagnetic ordering than Co, especially at low concentrations (1-2 %) of Cu where we realized near 100% polarization. But, the incorporation of Cu resulted in a 2-order of magnitude rise in the resistivity from 10-1 t.

Download or read book Zinc Oxide based Diluted Magnetic Semiconductors written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During my graduate research I have synthesized materials known as diluted magnetic semiconductors (DMS) as epitaxial thin film structures using the process of pulsed laser deposition (PLD). These materials are envisioned to be of importance in the emerging field of spintronics where the charge as well as the spin of the charge carriers can be combined to yield unique functionalities to yield novel devices including, on-chip memories, ultra-low power devices etc. The material of interest in this dissertation was zinc oxide, a wide bandgap optoelectronic semiconductor. ZnO has a bandgap of 3.3 eV. It is an ideal candidate for spintronics applications, because Zn is the last of the first row transition metals, which leads to pretty high solubility of transition metals such as Co, Mn and V in ZnO. In a diluted magnetic semiconductor a fraction of the host atoms is substituted by the transition metal dopant ion. We have found that we can synthesize very high quality, single phase and single crystalline Zn(TM)O thin films on basal plane sapphire single crystals (a-Al2O3). We have analyzed the magnetic properties of the three systems of ZnVO, ZnCoO and ZnMnO and found that ZnCoO and ZnMnO exhibit ferromagnetic ordering up to room temperature, when synthesized under high vacuum. In these conditions, the samples have a reasonable concentration of point defects which drive ZnO to n-type conductivity. By a combination of insitu and exsitu variation of parameters we have been able to tune the electronic and magnetic properties of these systems. From these studies we conclude that the main mechanism of magnetic ordering in these DMS materials is through a combination of defect related carrier induced exchange and bound magnetic polaron exchange. Device structures were fabricated using the as deposited samples to study the possibility of spin injection through semiconductors. We have observed that at low temperatures we see a considerable effect from this phenomenon in a m.

Download or read book Diluted Magnetic Semiconductor ZnO written by Kuldeep Chand Verma and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: For advancement in future spintronics, the diluted magnetic semiconductors (DMSs) might be understood for their origin of ferromagnetic aptness. It not much clear to the ferromagnetism in DMS, that is intrinsic or via dopant clustering formation. For this, we have included a review study for the doping of transition metal and rare earth ions in ZnO. It is realized that the antiferromagnetic ordering is found in doped ZnO to achieve high-TC ferromagnetism. X-ray diffraction and Raman spectra techniques have been used to detect the wurtzite ZnO structure and lattice defects. Since ZnO has different types of morphology formation that is generally dependent on synthesis conditions and dopant level. The band gap energy of ZnO and lattice defect formation are shown by photoluminescence technique. The room temperature ferromagnetism is described with bound magnetic polaron (BMP) model in which oxygen vacancies play a major role. However, the temperature-dependent conditions are responsible for ferromagnetic ordering. The first principle calculation is used for dopant ions in ZnO for their replacement of Zn2+ atoms in the wurtzite structure as well as magnetic contribution.

Download or read book Study of Diluted Magnetic Semiconductors written by Zlatko Micković and published by . This book was released on 2010 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition Metal Ions Doped Zno Nanopowders written by B. Babu and published by LAP Lambert Academic Publishing. This book was released on 2015-02-16 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intensive research on semiconductor nanomaterials has increased remarkably during the past years due to their unique characteristics. Wide-band gap oxide semiconductors have occupied the forefront because of an increasing need for short wavelength photonic devices, high-power, high-frequency electronic devices. Doping with proper metal elements via introducing acceptor or donor in host material is an effective approach to tune the materials with requisite properties. Among different magnetic semiconductor materials, 3d transition metal doped ZnO has received maximum attention due to the observation of room temperature ferromagnetism with suitable magnetic dopant ions. Therefore, selection of proper doping element in ZnO has become an important route for enhancing and controlling electrical, optical and magnetic performances of nanomaterials. The objective of the present investigation is to synthesis, structural, spectroscopic and magnetic properties of transition metal ions doped ZnO nanopowders by solid state reaction with sonochemical assistance. The synthesized powders are characterized by XRD, SEM, Optical absorption, PL, FT-IR, EPR and VSM techniques.

Download or read book Nanostructured Zinc Oxide written by Kamlendra Awasthi and published by Elsevier. This book was released on 2021-08-10 with total page 781 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured Zinc Oxide covers the various routes for the synthesis of different types of nanostructured zinc oxide including; 1D (nanorods, nanowires etc.), 2D and 3D (nanosheets, nanoparticles, nanospheres etc.). This comprehensive overview provides readers with a clear understanding of the various parameters controlling morphologies. The book also reviews key properties of ZnO including optical, electronic, thermal, piezoelectric and surface properties and techniques in order to tailor key properties. There is a large emphasis in the book on ZnO nanostructures and their role in optoelectronics. ZnO is very interesting and widely investigated material for a number of applications. This book presents up-to-date information about the ZnO nanostructures-based applications such as gas sensing, pH sensing, photocatalysis, antibacterial activity, drug delivery, and electrodes for optoelectronics. - Reviews methods to synthesize, tailor, and characterize 1D, 2D, and 3D zinc oxide nanostructured materials - Discusses key properties of zinc oxide nanostructured materials including optical, electronic, thermal, piezoelectric, and surface properties - Addresses most relevant zinc oxide applications in optoelectronics such as light-emitting diodes, solar cells, and sensors

Download or read book Development of Transition metal Doped Cu2O and ZnO Dilute Magnetic Semiconductors written by Mathew P. Ivill and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Mn solubility in Cu2O was found to be small and the precipitation of Mn-oxides was favored at high growth temperatures. Phase pure Mn-doped Cu2O samples were found to be non-magnetic. Samples were p-type with carrier concentrations on the order of 1014-1016 cm−3.

Download or read book Handbook of Spin Transport and Magnetism written by Evgeny Y. Tsymbal and published by CRC Press. This book was released on 2016-04-19 with total page 797 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past several decades, the research on spin transport and magnetism has led to remarkable scientific and technological breakthroughs, including Albert Fert and Peter Grunberg's Nobel Prize-winning discovery of giant magnetoresistance (GMR) in magnetic metallic multilayers. Handbook of Spin Transport and Magnetism provides a comprehensive, bal

Download or read book Zinc Oxide written by Hadis Morkoç and published by John Wiley & Sons. This book was released on 2008-12-03 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first systematic, authoritative and thorough treatment in one comprehensive volume presents the fundamentals and technologies of the topic, elucidating all aspects of ZnO materials and devices. Following an introduction, the authors look at the general properties of ZnO, as well as its growth, optical processes, doping and ZnO-based dilute magnetic semiconductors. Concluding sections treat bandgap engineering, processing and ZnO nanostructures and nanodevices. Of interest to device engineers, physicists, and semiconductor and solid state scientists in general.

Download or read book Annealing Studies on the Structural and Magnetical Properties of Co Implanted Zno Single Crystal written by Lanlan Zou and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Annealing Studies on the Structural and Magnetical Properties of Co Implanted ZnO Single Crystal" by Lanlan, Zou, 邹兰兰, 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: As a wide band gap semiconductor, Zinc Oxide (ZnO) has recently attracted considerable attention due to its wide applicability. Transition metal (TM) doped ZnO is one of the most intensive research field in the last decade because of its possible application in spintronics devices. The Co-implanted ZnO has been considered as one of the most promising candidate in the field of diluted magnetic semiconductor (DMS). In this study, the magnetic and structural properties of Co-implanted ZnO single crystal were investigated. ZnO single crystals were implanted with 100 keV-Co ions at 300K with a fluence of 1014cm-2and subsequently annealed at 750oC and 900oC respectively. The samples were studied by secondary ion mass spectrometry, X-ray diffraction, photoluminescence, X-ray photoemission spectroscopy and vibrating sample magnetometer. The as-implanted sample seemed to be phase pure while the spinel secondary phase ZnCo2O4 was present in 750oC and 900oC samples showed trace ofCo3O4, Zn0.52Co2.48O4 and metallic Co cluster. All the samples exhibited ferromagnetism at room temperature in low field region, and the magnetic moment was found to decrease and increase after the heat treatment. In high field region, typical paramagnetism was the dominating magnetic property. More than one ferromagnetic mechanism is involved to explain the experimental results. DOI: 10.5353/th_b4979969 Subjects: Zinc oxide Annealing of crystals

Download or read book Transition Metal Doped ZnO Synthesis Structural and Optical Properties written by Sajid Husain and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will provide a good understanding to readers about the chemical synthesis process of un-doped and doped ZnO nanoparticles. The various characterization has been done which emphasize to optoelectronic application on the basis of band gap tuning. And it has an immense application in DMS materials also. The additional information includes in the APPENDICES-A & B which might be useful for synthesis and the energy band gap calculation with theoretical reference.

Download or read book Transition Metal Doped ZnO for Spintronics written by and published by . This book was released on 2007 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this project, the properties of transition metal (TM) -doped ZnO will be investigated. The project focuses on two activities. First, the properties of ZnO doped with transition metals (Mn, Co, or Cr) and deep level impurities (Cu, As, Sn) is explored. The primary interest will be on elucidating the origin of magnetism in the TM-doped material, including understanding the role of deep level co-dopants in mediating ferromagnetism. Experiments will focus on correlating magnetic properties (Curie temperature, moment/TM dopant) with the TM and deep level dopant concentrations. Epitaxial film growth and ion implantation of single crystals will be used in these studies. Second, for the dilute magnetic semiconducting compounds, there appears to be a correlation of Curie temperature with semiconductor bandgap. In an effort to increase the Curie temperature to greater than 300 K, the properties of TM-doped (Zn, Mg)O will also be investigated, as the addition of Mg to ZnO increases the bandgap. The epitaxial films will be grown by pulsed-laser deposition. Temperature-dependent Hall and resistivity measurements will be used to determine conduction mechanisms, carrier type, and doping. SQUID magnetometry will be used to characterize the magnetic properties of transition metal doped materials.

Download or read book Physical Properties of Dilute Magnetic Semiconducting Oxides written by Sudipta Bandyopadhyay and published by LAP Lambert Academic Publishing. This book was released on 2014-11-19 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal doped ZnO has been studied from the perspective of its suitability in electronic applications. Bulk samples of Mn doped ZnO has been synthesized by solid state reaction and sol-gel techniques. Thin films of Mn doped ZnO has been synthesized by only sol-gel spin coating technique. So far as Co doped ZnO is concerned it is basically Co co-doped AZO [Al doped ZnO] film synthesized by sol-gel dip coating technique. Above 3 at% of Mn doping impurity phase has been developed for bulk powder sample. The impurity phase was completely or partially dissolved by ion beam irradiation. The role of Zn vacancy and substitutional replacement of Mn at Zn site is crucial for intrinsic ferromagnetism. Further counterbalancing antiferromagnetism and paramagnetism are also present. 2 at% Mn doped ZnO powder sample indicate metal insulator transition. Mn doped ZnO films exhibit defect induced ferromagnetism and interpreted in terms of bound magnetic polaron. Zn Vacancy favours and oxygen vacancy opposes intrinsic ferromagnetism in Mn doped ZnO film. Highly conducting Co co-doped AZO films shows potential for applications with interesting low temperature resistivity behaviour.

Download or read book Investigations on Transition Metal Doped Semiconductor for Spintronics written by Reddithota Vidya Sagar and published by LAP Lambert Academic Publishing. This book was released on 2010-10 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Present thesis entitled "Studies on Synthesis, Structural, Optical and Magnetic Properties of Mn, Co, and (Mn, Co) Substituted ZnO nanoparticles has been compiled in six chapters. Chapter I, brings out a general and necessary introduction to understand the basic concepts and significance of the topic of research. Chapter II, describes the experimental studies carried upon by the author in the synthesis and analysis of Mn, Co and (Mn, Co): ZnO nanoparticles by means of a single-source oxalate precursor decomposition method. Chapter III, reports on the results based on the synthesis, structural, optical and magnetic properties of Mn: ZnO nanoparticles. The magnetic properties of the samples have been carried out on a Vibrating Sample Magnetometer (VSM). Chapter IV documents the results concerning the synthesis, structural, optical and magnetic properties of Co: ZnO nanoparticles. Room temperature ferromagnetism was confirmed used VSM. Chapter V reports the results pertaining to the synthesis, structural, optical and magnetic properties of (Mn, Co): ZnO nanoparticles. Chapter VI is the summery of the thesis