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Phonon Scattering through a Local Anisotropic Structural Disorder in the Thermoelectric Solid Solution Cu_2Zn_(1−x)Fe_xGeSe_4
2013
Inspired by the promising thermoelectric properties of chalcopyrite-like quaternary chalcogenides, here we describe the synthesis and characterization of the solid solution Cu(2)Zn(1-x)Fe(x)GeSe(4). Upon substitution of Zn with the isoelectronic Fe, no charge carriers are introduced in these intrinsic semiconductors. However, a change in lattice parameters, expressed in an elongation of the c/a lattice parameter ratio with minimal change in unit cell volume, reveals the existence of a three-stage cation restructuring process of Cu, Zn, and Fe. The resulting local anisotropic structural disorder leads to phonon scattering not normally observed, resulting in an effective approach to reduce th…
Electron–phonon effects on the direct band gap in semiconductors: LCAO calculations
2002
Abstract Using a perturbative treatment of the electron–phonon interaction, we have studied the effect of phonons on the direct band gap of conventional semiconductors. Our calculations are performed in the framework of the tight-binding linear combination of atomic orbitals (LCAO) approach. Within this scheme we have calculated the temperature and isotopic mass dependence of the lowest direct band gap of several semiconductors with diamond and zincblende structure. Our results reproduce the overall trend of available experimental data for the band gap as a function of temperature, as well as give correctly the mass dependence of the band gap on isotopic. A calculation of conduction band in…
Rotating magnetic fields as a means to control the hydrodynamics and heat/mass transfer in the processes of bulk single crystal growth
1999
The report discusses the possibility of using different types of rotating magnetic fields (RMF) and combinations of these to control the hydrodynamics and heat/mass transfer in the processes of bulk semiconductor single crystal growth. Some factors contributing to the efficiency of RMF influence in different technologies are analysed. Their specific practical application is illustrated by some examples.
Semiconducting half-Heusler and LiGaGe structure type compounds
2009
Compounds with LiAlSi (half-Heusler) and LiGaGe structure types have been investigated by means of band structure calculations. The LiAlSi structure type is known as the half-Heusler structure type, whereas LiGaGe is a closely related hexagonal variant. A remarkable feature of some XYZ half-Heusler compounds with 8 and 18 valence electrons is, that despite being composed of only metallic elements, they are semiconductors. More than 100 semiconducting compounds within these structure types are known. LiGaGe compounds have an additional degree of freedom, namely the degree of puckering of the layers. These compounds can become semiconducting at a certain degree of puckering. Half-metallic beh…
Photoemission of electrons into electrolyte from cadmium oxide layers formed by anodic oxidation of undeformed and plastically deformed cadmium plates
1995
Studies of electron emission (external photoeffect) at the electrode/solution interface are an important part of contemporary photoelectrochemistry. The results of systematic studies of this phenomenon led to the formulation of fundamental relationships and to new methods for investigation of the physicochemical processes occurring at the electrode-electrolyte interface [1-4]. In particular, photoemission measurements enabled a number of parameters relating to the structure of the semiconductor/electrolyte interface to be determined. The photoemission current from semiconductors with many surface states to solutions with a sufficiently high electrolyte concentration is described by the well…
Third-Generation Solar Cells: Concept, Materials and Performance - An Overview
2019
The large scarcity of natural fuels in earth crust has triggered to search alternative energy reservoirs for the future generation of human life. Because of large abundancy, solar energy is considered as big hope for the future generation energy utilization for commercial as well as home applications. The scientific revolution achieved in synthesis and processing of semiconductor nanomaterials, organic conducting polymers have led into new dimension in fabrication of future-generation solar cells. Reduction in the dimension of semiconductor nanomaterials significantly influences on their structural and optical properties which is helpful for the excellent photon harvesting. Also, their larg…
Biochemical Applications of Solid Supported Membranes on Gold Surfaces: Quartz Crystal Microbalance and Impedance Analysis
2003
Since their inception in 1985 by Tamm and McConnell [1], solid supported lipid bilayers have been widely used as model systems for cellular membranes [2]. They have been applied in fundamental and applied studies of lipid assemblies on surfaces, to study the structure of membranes and membrane dynamics, lipidreceptor-interactions and electrochemical properties of membranes [3-5]. Several attempts have been made to apply solid supported membranes (SSM) in biosensor devices [6]. Planar lipid membranes can be formed on various surfaces, i.e. glass, silicon, mica or metal surfaces such as platinum or gold. Surface attachment of the lipids is typically achieved following two different strategies…
Oligothiophenes for Pattern Formation by Stamping
2003
Oligothiophene monomers with a fixed length varying from 3 to 5 thiophene rings were prepared by Stille coupling. They were functionalised with one or two methacrylate groups to allow polymerization and cross-linking. These monomers can be patterned with the help of soft silicon stamps (e.g., with the micro-injection moulding in capillaries process) on substrates like glass or flexible polymer foils. If a photoinitiator has been added, they can then be hardened by exposure to UV-light through the transparent stamp. Afterwards the stamp can be removed. This allows the preparation of several centimeters long oligothiophene lines of a width varying between 50 and 0.5 μm. These lines of semicon…
<title>Proton conducting polymer electrolytes for electrochromic devices</title>
1997
This report concerns a composite proton electrolyte suitable for use in electrochromic devices. The electrolyte consists of nanosize hydrated oxide (aluminum, silicon or antimonic) particles suspended in a poly(vinyl acetate) matrix. All of the water was strongly bonded, thus making the electrolytes less harmful without considerably decreasing the conductivity. The proton conductivity of the electrolyte was approximately 10-4 S/cm at room temperature, practically independent of its amount of absorbed water.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Characterization of the LGBTI-speaking community discourse. An approach to Hispanic queer linguistics.
2020
Toda subcultura forma una comunidad lingüística particular en la que, aunque se comparta la lengua con el resto de la sociedad, varía el habla en ciertos aspectos. Es el caso de la comunidad de habla LGTBI, que se hace servir de un léxico peculiar, así como una fraseología característica, unas estructuras gramaticales especiales y, en definitiva, unos recursos pragmáticos muy llamativos que tienen como objetivo mitigar ciertos enunciados, intensificar otros en determinados contextos y construir actos de habla afiliativos que expresen solidaridad social. Por otro lado, cumple una función muy importante en la construcción identitaria de sus usuarios. En este trabajo se propone un análisis pra…