Seed layers for the growth of oriented vertical arrays of ZnO nanorods

ZnO is a direct wide bandgap semiconductor crystallizing in the wurtzite structure with a series of unique properties: a large exciton binding energy; good optical transmittance in the visible region; high optical gain; piezoelectricity; room temperature ferromagnetism; mechanical stability given by the high melting point and large cohesive energy; radiation hardness; or biological compatibility. These properties allow for applications of ZnO in UV light-emitting devices and detectors, field-effect transistors, solar cells, piezoelectric nanogenerators, or chemical sensors. For the majority of these applications, upright standing arrays with controlled positioning, sizes, and physical properties are preferred. Chemical bath deposition (CBD) is a low-cost, low-temperature, surface scalable technique to grow ZnO nanostructures on virtually any substrate with a suitable seed layer. We show how the properties of the seed layer such as the texture, roughness, and porosity affect the nucleation and the alignment of ZnO nanorods (fig. 1a,b). The ZnO seed layers were prepared by electrophoretic deposition of a commercially available solution of ZnO nanoparticles dispersed in ethanol and by the sol-gel method, where the seed layers deposited by dip coating of a chemical precursor solution obtained by dissolving zinc acetate dihydrate and monoethanolamine in 2-methoxyethanol onto a (100) Si substrate. The film thickness, porosity, texture, and the size of the crystallites were controlled by varying the molar concentration of precursors, the withdrawal speed, and the number of dip-coating cycles. The ZnO nanorods were grown by CBD in aqueous solution consisting of zinc nitrate hexahydrate and HMTA in batch and continuous-flow reactors. Periodic arrays of ZnO nanorods were obtained on the seed layers patterned by electron or ion beam lithography (fig. 1c). To study the electric charge transport in the nanorods, electrical contacts were formed by the deposition of colloidal graphite, by metal evaporation and by the deposition of Pt using the gas injection system in the SEM. The transport properties were correlated with the structural and optical properties investigated by x-ray diffraction and low-temperature photoluminescence spectroscopy. Please click Additional Files below to see the full abstract

Ballistic electron emission microscopy of InAs quantum dots in AlGaAs/GaAs heterostructure

Ballistic electron emission measurements of InAs/GaAs quantum dots in AlGaAs/GaAs heterostructures are presented in our contribution. Measured heterostructure was prepared by MOCVD technique. The area of 1 μm.sup.2./sup. was analyzed during measurements. Different size and shape of quantum dots on an examined area were vizualized. The average size of quantum dots were 10 nm and less. The observed shapes are probably connected with density of states in quantum dots

Strategic analysis of ČEZ Distribuce, a.s.

Tato bakalářská práce se zabývá analýzou společnosti ČEZ Distribuce, a.s., působící na českém distribučním trhu s elektrickou energií ve strategické rovině s cílem poskytnou čtenáři komplexní informace nejen o analyzované společnosti, ale i o odvětví samotném pohledem externího analytika. Práce je rozdělena na dva celky, část teoretickou a praktickou. V teoretické části jsou popsány základní pojmy a informace potřebné k analýze samotné. Důraz je kladen na části věnující se definování firemní strategie, mikro i makrookolí společnosti, ekonomické analýze zahrnující analýzu finanční a analýzu naturálních ukazatelů a v neposlední řadě na souhrnnou SPACE a SWOT analýzu. Praktická část je zaměřena již na aplikaci těchto analytických nástrojů na vybranou společnost a odvětví. Tato část práce má za úkol čtenáři osvětlit základní principy, bariéry či trendy ve zkoumané části ekonomiky. Krom toho je v praktické části (zejména v ekonomické analýze) kladen důraz na srovnání s ostatními dvěma distributory elektrické energie působícími na českém trhu.The goal of this Bachelor's Thesis is to conduct a strategic analysis of ČEZ Distribuce, a.s., which is part of the biggest Czech energy group. It provides the reader with detailed information about the power distribution company itself as well as the Czech power distribution sector from the point of view of an external analyst. The thesis is divided into two parts: theoretical and practical. The first part gives information about the fundamental terms and mechanisms needed for the analysis itself. The focus is on definition of corporate strategy, analysis of micro and macro environments, economic analysis and summarizing SPACE and SWOT analyses. The second part aims to apply the above mentioned analytical methods to the particular case of ČEZ Distribuce, a.s. and the power distribution sector. It clarifies the main principles, barriers and trends in the power distribution sector in the Czech Republic. Additionally, the thesis stresses comparison with rest of the competitors performing on the Czech market (especially in the economic analysis part)

Preliminary balistic electron emission microscopy/spectroscopy characterization of InAs quantum dots in AlGaAs/GaAs heterostructure

We presented a characterization of InAs self assembled quantum dots embedded in quantum well of the AlGaAs/GaAs heterostructure using ballistic electron emission microscopy/spectroscopy BEEM/BEES. Structures are grown by MBE. Results of spectroscopic measurements "on the dot" and "out of the dot" are also presented

Multichannel formats for music recording

Práce se zabývá problematikou reprodukce prostorového zvuku ve formátu 5.1 pomocí sluchátek. V úvodu práce je zmíněno teoretické pozadí prostorového zvuku. Práce zde popisuje prostorové vlastnosti zvuku a principy, díky kterým je člověk schopný lokalizovat zdroj zvuku v prostoru. Dále se věnuje reprodukci zvuku pomocí surroundové konfigurace 5.1. Zmiňuje také způsoby, kterými lze dosáhnout prostorového zvuku při reprodukci pomocí sluchátek. Stěžejní částí práce je psychoakustický poslechový experiment, jehož cílem je zjištění kvality lokalizace zdroje zvuku v transverzální rovině při reprodukci 5.1 signálu pomocí sluchátek. Zde je v práci zmíněná metodologie a samotný průběh experimentu, analýza naměřených dat a jejich výsledná interpretace. Naměřená data prokazují, že lokalizace azimutu v celém prostoru kolem posluchače je při reprodukci 5.1 signálu na sluchátka možná

Latentní sémantická analýza kodexů správy společností členských zemí OECD a G20

Tato diplomová práce se zabývá kvantifikací konvergence kodexů správy společností se zaměřením na členské země OECD a skupiny G20. Práce je rozdělena na teoretickou a praktickou část. V teoretické části jsou rozvinuty okruhy týkající se správy společností, jejich kodexů a rešerše vědeckých článků publikovaných na podobné téma. Práce má stanovené dva cíle. Zaprvé kvantifikaci konvergence národních kodexů k Principům OECD pro správu a řízení podniků a zadruhé kvantifikaci konvergence národních kodexů mezi sebou. Toho je dosaženo pomocí identifikace klíčových klastrů témat, které se prolínají napříč textem všech kodexů, a dále pomocí analýzy důležitosti těchto témat v jednotlivých kodexech a jejich vývoj v čase. Použitou metodou je latentní sémantická analýza, která je statistickým přístupem pro analýzu vztahů mezi sadou dokumentů a termíny v dokumentech obsažených, za pomocí vytvoření pojmů souvisejících s těmito dokumenty a termíny. Programovacím jazykem použitým v této práci je R.This thesis deals with quantifying convergence of corporate governance codes with the focus on OECD and G20 member countries. The thesis consists of theoretical and practical part. Theoretical part develops key terminology of corporate governance, corporate governance codes and later it also reviews scientific papers published on similar topics. There are two main goals for this thesis. Firstly, to quantify convergence of country codes towards the OECD Principles of Corporate Governance and secondly, to quantify convergence of nation codes between each other. This is done through identifying dominant themes in the whole corpus, analysis of weights of those themes in each country code and their evolution in time. The methodology used in thesis is Latent Semantic Analysis which is a statistical and mathematical technique for analyzing relationships between a set of documents and the terms they contain by producing a set of concepts related to the documents and terms. The programming language used in this thesis is R

Scanning thermal microscopy of thermoelectric pulsed laser deposited nanostructures

New materials with high possible figure of merit ZT are of high interest as a promising candidates for thermoelectric applications such as energy harvesting. Miniaturization of such systems tends toward developing of the suitable characterization method with nanometer resolution ability. In our contribution, we present the development and experimental results of a simple scanning probe microscopy method for the relative thermal conductivity characterization. The possibility of the setup is demonstrated on the set of different thin thermoelectric layers grown from hot pressed targets by pulsed laser deposition on the reference Si substrate. All the measurements were performed on the commercial Veeco Multimode scanning AFM/STM microscope with home developed controller and by using PicoCal Inc. bolometer probes with tungsten resistive path. All the experiments were done in the air at the ambient condition. Additional sample treatment for the measurement will be also briefly describe

Comparing numerical integration schemes for a car-following model with real-world data

summary:A key element of microscopic traffic flow simulation is the so-called car-following model, describing the way in which a typical driver interacts with other vehicles on the road. This model is typically continuous and traffic micro-simulator updates its vehicle positions by a numerical integration scheme. While increasing the order of the scheme should lead to more accurate results, most micro-simulators employ the simplest Euler rule. In our contribution, inspired by [1], we will provide some additional details that have to be addressed when implementing higher-order numerical integration schemes for CFMs and we will show that the theoretical gain of higher-order methods is unfortunately masked out by the stochastic nature of real-world traffic flow