Search results for "OEL"
showing 10 items of 5270 documents
Incorporación de elementos traza en conchas de melanopsis durante el crecimiento : posibilidades de aplicación en paleoecología
1988
El objetivo del presente trabajo está encaminado al estudio de las variaciones de oligoelementos en la concha de un gasterópodo de agua dulce del género Melanopsis (U dufouri (FERUSSAC), con dos morfotipos) y si éstas tienen que ver, o no, con la fluctuación de una serie de parámetros ambientales. La importancia del trabajo radica en la posibilidad de la aplicación paleoecológica de sus resultados, ya que el género MelanopsÍs tiene un abundante registro fósil durante todo el Cenozoico. La incorporación de oligoelementos se efectúa a medida que la concha va creciendo por acreción; lo ideal sería que tal crecimiento fuera circadiano, ya que se podría seguir día a día, sobre la concha, la fluc…
Ar Er3+ un Yb3+ aktivētu savienojumu uz Na0,5Bi0,5TiO3 bāzes, luminiscences intensitātes modulācija ar elektrisko lauku
2021
Na0,5Bi0,5TiO3 tiek pētīts kā perspektīvs materiāls svinu saturošu segnetoelektrisko materiālu aizvietošanai, pateicoties tā strukturālajām izmaiņām temperatūras vai elektriskā lauka ietekmē, to var izmantot ar elektrisko lauku vadāmās ierīcēs. Darbā tika pētīta ar Er3+ un Yb3 aktivētu Na0.5Bi0.5TiO3 cieto šķīdumu augšup pārveidotās luminiscences intensitātes modulācija, un raksturoti tās iespējamie mehānismi. Paraugu sintēzei, apstrādei, raksturošanai un luminiscences intensitātes modulācijas eksperimentiem tika izmantotas LU Cietvielu fizikas institūtā pieejamās iekārtas. Darbs sastāv no četrām nodaļām - literatūras apskata, metodiskās daļas, eksperimentālās daļas un secinājumiem. Izmanto…
Influence of a Thiolate Chemical Layer on GaAs (100) Biofunctionalization: An Original Approach Coupling Atomic Force Microscopy and Mass Spectrometr…
2013
International audience; Widely used in microelectronics and optoelectronics; Gallium Arsenide (GaAs) is a III-V crystal with several interesting properties for microsystem and biosensor applications. Among these; its piezoelectric properties and the ability to directly biofunctionalize the bare surface, offer an opportunity to combine a highly sensitive transducer with a specific bio-interface; which are the two essential parts of a biosensor. To optimize the biorecognition part; it is necessary to control protein coverage and the binding affinity of the protein layer on the GaAs surface. In this paper; we investigate the potential of a specific chemical interface composed of thiolate molec…
Simulations of Piezoelectric, Electronic and Optical Properties of Nanowires
2016
Los nanohilos semiconductores han atraido un interés creciente debido a sus potenciales aplicaciones en electrónica, óptica y fotónica. Un amplio rango de dispositivos fotónicos y electrónicos basados en nanohilos han sido ya demostrados, incluyendo células solares, fotodetectores, diodos emisores de luz, y láseres. Para comprender las propiedades de los nanohilos es necesario conocer su estructura electrónica. Además, es importante conocer cómo estas propiedades dependen del tamaño, estructura cristalina y orientación, y cómo se ven afectadas por las deformaciones. El objetivo de esta tesis es desarrollar modelos teóricos realistas, pero manejables desde un punto de vista computacional, pa…
Low toxicity metal halide semiconductors for optoelectronics and thermoelectrics
2023
Amb la finalitat de lluitar contra el canvi climàtic i donar suport a les energies renovables i no contaminants, l'objectiu principal d'aquesta tesi és la cerca i l'estudi de nous materials amb potencial aplicació en tres grans àrees d'investigació: la fotovoltaica, la termoelèctrica i els díodes emissors de llum (LED). Atés que molts dels materials emprats en aquestes àrees contenen components tòxics i nocius per al medi ambient, els materials desenvolupats en aquesta tesi a més presenten una baixa toxicitat i es poden preparar mitjançant mètodes de síntesis i deposició més sostenibles i ecològics. Concretament, es van utilitzar dos mètodes de síntesis: la mecanosíntesi en sec per molta de…
Charge Transport Mechanisms in Heavy-Ion Driven Leakage Current in Silicon Carbide Schottky Power Diodes
2016
Under heavy-ion exposure at sufficiently high reverse bias voltages silicon carbide (SiC) Schottky diodes are observed to exhibit gradual increases in leakage current with increasing ion fluence. Heavy-ion exposure alters the overall reverse current-voltage characteristics of these diodes, leaving the forward characteristics practically unchanged. This paper discusses the charge transport mechanisms in the heavy-ion damaged SiC Schottky diodes. A macro model, describing the reverse current-voltage characteristics in the degraded SiC Schottky diodes is proposed. peerReviewed
Effect of the Si doping on the properties of AZO/SiC/Si heterojunctions grown by low temperature pulsed laser deposition
2020
Abstract The structural and photoelectrical properties of Al-doped ZnO (AZO)/SiC/p-Si and AZO/SiC/n-Si heterojunctions, fabricated at low temperature by pulsed laser deposition, were investigated by means of a number of techniques. Raman analysis indicates that SiC layers have the cubic 3C-SiC phase, whilst X-ray diffraction measurements show that AZO films exhibit a hexagonal wurtzite structure, highly textured along the c-axis, with average crystallites size of 35.1 nm and lattice parameter c of 0.518 nm. The homogeneous and dense surface morphology observed by scanning electron microscopy was confirmed by atomic force microscopy images. Moreover, UV–Vis-NIR spectra indicated a high trans…
Particle radiation in microelectronics
2012
The unavoidable presence of particle radiation in space and on the ground combined with constantly evolving technology necessitates a deep understanding of the basic mechanisms underlying radiation effects in materials and electronic devices. This thesis provides an overview of the different radiation environments, with a review of the interaction mechanisms between energetic particles and matter. In this work a new semi-empirical model for estimating the electronic stopping force of solids for heavy ions is introduced. Radiation effects occurring in microelectronics due to particle radiation are also discussed with a brief introduction to radiation hardness assurance (RHA) testing of elect…
Amorphous silicon nanotubes
2017
In the following, the attention will be focused on the silicon nanotube (SiNTs) that is a highly desired form of silicon for its fundamental role in the miniaturization trend of the electronic devices. After a description of the properties and applications of SiNTs and their fabrication methods, the attention will be focused on chemical vapour deposition (CVD) template synthesis that is the most usual synthetic method for this material. Then, galvanic template synthesis will be described as a general method for the fabrication of different metals and oxides nanostructures, therefore the use of this technique for synthesizing SiNTs will be detailed. Characterization methods will be also desc…
Silīcija kristālu audzēšanas procesa videomateriāla apstrāde
2017
Darbs ir veltīts mašīnu redzes sistēmai, kas nodrošina lietņa diametra svārstību kontroli silīcija kristālu audzēšanas metodei, ko Latvijā bāzēts uzņēmums SIA "KEPP EU" izmanto saules bateriju kategorijas monokristālu ražošanai. Darba galvenie mērķi ir: izpētīt izmantoto silīcija kristālu ražošanas metodi, iepriekšējus EDI un KEPP EU veiktos pētījumus, kas rezultēja apskatītās mašīnu redzes sistēmas izstrādē, un uzlabot tās attēlu apstrādes algoritmus, lai uzlabotu specifiskas metrikas noteikšanas precizitāti un ātrdarbību. Darbā tiek aprakstītas populārākas silīcija kristālu audzēšanas metodes, izstrādātā mašīnu redzes sistēma un attēlu apstrādes algoritmi, ko darba autors izmantoja uzlabo…