Download or read book First Principles Study on the Effects of Vacancies and Mg Doping on the Physical Properties of CuAlO2 AgAlO2 CuCrO2 and AgCrO2 Transparent Conductor Oxides written by James A. Shook and published by . This book was released on 2018 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for well understood, commercially available p-type transparent conducting oxides for incorporation into basic transparent semiconducting devices alongside their already well understood and available n-type counterparts for application in technologies such as solar cells and capacitive touchscreens motivates this first principles study on the effects of Cu and O vacancies and Mg doping on the intrinsically poor p-type character of CuAlO2, AgAlO2, CuCrO2, and AgCrO2. Density functional theory based calculations using the projector augmented-wave functions along with the generalized gradient approximation to the exchange and correlation energy as implemented by the Vienna Ab Initio Simulation Package are used to study the total crystal energy of the three known polymorphs of CuAlO2 and AgAlO2 in order to determine the most stable polymorph in the ground state. Additionally, three simple magnetic configurations are considered for CuCrO2 and AgCrO2 in the context of total energy of the ground state for the purpose of choosing a specific polymorph and magnetic configuration to be the framework within which the doped and defect systems will be studied. Different functional approaches to the exchange and correlation energies are also considered in order to accurately reproduce the structural properties and the band gap. The 2H delafossite polymorph is determined to be one of the most stable polymorphs and is the focus of this work as it is the least studied of the delafossites. The simple antiferromagnetic configuration is chosen to model magnetic effects in CuCrO2 and AgCrO2 due to it having one of the lowest ground state total energies and also containing the most semiconductor like behavior of the magnetic configurations considered. A 2x2x2 supercell scheme is employed to model 6.25% Cu and Ag vacancies, 3.13% O vacancies, and 6.25% Mg-doping replacing Al and Cr, from which structural properties, electronic properties, hole effective masses, and optical properties are obtained and compared to the pristine crystal in order to offer predictions on the effectiveness of the mentioned native defects and dopant on increasing the conductivity and maintaining transparency in all transparent conducting oxides studied in this work. Comparisons between the results obtained in this work and previous experimental and other theoretical results are made, when available. Many of the properties predicted here are immediately testable via experimentation.

Download or read book First Principles Studies on N type and P type Doping in Cuprous Oxide written by Qiong Bai and published by . This book was released on 2015 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have performed studies on n-type and p-type cuprous oxide with and without doping by first principles methods. Generalized Gradient Approximation (GGA) is used for the geometry optimization. The total energy and the final electronic structure calculations are conducted using the nonlocal screened Heyd-Scuseria-Ernzerhof (HSE) hybrid density functionals approach for cuprous oxide. The HSE hybrid density functionals overcome the shortcoming of GGA, which gives a much reliable value of the band gap. The formation energies of native point defects in undoped cuprous oxide have been studied by HSE hybrid functional theory in two conditions, which are vacuum based condition and solution based condition. Copper vacancy always has the lowest formation energy and provides p-type conductivity in both Cu-rich and O-rich conditions in vacuum based conditions. In the solution with low pH value, n-type cuprous oxide is achievable, where the antisite defect CuO is the dominant defect and responsible for the n-type conduction. Various elements are used to dope in cuprous oxide. In n-type doped cuprous oxide, certain halogen atoms, i.e., F, Cl and Br, are used to substitute the O atom. The metallic atoms, i.e., Ca, Mg, and Zn, are used to substitute Cu atom. The dopant in substitutional site has lower formation energy. Cl has the shallowest defect level among halogen atoms, which is favorable for electron to go to conduction band. In metallic atoms, Ca is the best candidate dopant with low formation energy and shallow transition level. The extra electron can be excited into bottom of conduction band. Also, the bottom of conduction band is dominated by 3s orbital of O atom, which is non-localized. The excited electron can move fast in 3s orbital and further improve the conductivity. For p-type doping to improve the properties of the p-type material, certain group V elements, such as N, P and As, are used to substitute an O atom. In a solution with pH=9, the formation energy of nitrogen substitutional defect is lower than that of copper vacancy, which means that nitrogen substitutional defect is a dominant defect and provides more free carriers, and further improves the conductivity of cuprous oxide. From the consideration of both the formation energy and the donor level, N is the best dopant among these three dopants. Finally, n-type doping in ZnO by Y has been studied. Oxygen vacancies, zinc interstitials, and zinc substitution by Y are considered here. We considered the formation energy of defects from two limit conditions, which are Zn-rich and O-rich. In Zn-rich condition, copper vacancy has the lowest formation energy. In O-rich condition, yttrium substitutional has the lowest formation energy and is a dominant defect, which will decrease the resistivity of ZnO.

Download or read book Handbook of Transparent Conductors written by David S. Ginley and published by Springer Science & Business Media. This book was released on 2010-09-11 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transparent conducting materials are key elements in a wide variety of current technologies including flat panel displays, photovoltaics, organic, low-e windows and electrochromics. The needs for new and improved materials is pressing, because the existing materials do not have the performance levels to meet the ever- increasing demand, and because some of the current materials used may not be viable in the future. In addition, the field of transparent conductors has gone through dramatic changes in the last 5-7 years with new materials being identified, new applications and new people in the field. “Handbook of Transparent Conductors” presents transparent conductors in a historical perspective, provides current applications as well as insights into the future of the devices. It is a comprehensive reference, and represents the most current resource on the subject.

Download or read book Green Production of Carbon Nanomaterials in Molten Salts and Applications written by Ali Reza Kamali and published by Springer Nature. This book was released on 2020-01-10 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the possible interactions that might occur between carbon materials and molten salts, and discusses the mechanisms involved in detail, highlighting possible future developments in the field. Carbon materials can be exposed to molten salts in various technologically important applications, such as in molten salt-nuclear reactors and aluminum production electrolysis cells. As such, numerous studies have investigated the possible interactions between carbon and molten salts. In addition, various interesting carbon nanostructures have recently been produced in molten salts, including carbon nanotubes, graphene and nanodiamonds with a number of attractive applications. With abundant images and graphs supporting the discussion, this book appeals to researchers working in the field of carbon nanostructures, carbon capture and conversion, nuclear reactors, energy storage, molten salts and related areas of science and technology.