This thesis work reports an experimental analysis of TiOx nanostructures and ultrathin films on the Au(111) surface by means of Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The TiOx/Au(111) system is obtained with the electron-beam evaporation technique at low and high coverage, namely 0.3 ML and 1.5 ML of titanium, followed by oxidation. The STM analysis shows the formation of five different TiOx phases, in agreement with previous observations, whose structural and morphological features are discussed thanks to atomically resolved STM images and the results of Low Energy Electron Diffraction (LEED) measurements. The STS analysis, on the other hand, allows to investigate the electronic properties of the TiOx phases and it shows their peculiar individual features around the Fermi energy. The examined system represents a model system for the study of morphological, structural and electronic properties of nanostructured TiOx films, which, thanks to their high surface/volume ratio, are highly regarded in the research on photovoltaic and photocatalytic applications.
Il presente elaborato di tesi riporta un'analisi sperimentale della crescita di nanostrutture e film ultrasottili di TiOx su Au(111) tramite microscopia a effetto tunnel (STM, Scanning Tunneling Microscopy) e spettroscopia a effetto tunnel (STS, Scanning Tunneling Spectroscopy). Il sistema TiOx/Au(111) è stato ottenuto con la tecnica di evaporazione da fascio elettronico a basso ed alto coverage di titanio, principalmente 0.3 ML e 1.5 ML, seguita da ossidazione. L'analisi STM mostra la formazione di cinque diverse fasi di TiOx, in accordo con le precedenti osservazioni, le cui caratteristiche strutturali e morfologiche sono discusse grazie alle immagini STM a risoluzione atomica e i risultati ottenuti dalla diffrazione elettronica a basse energie (LEED, Low Energy Electron Diffraction). L'analisi STS, invece, consente di investigare le proprietà elettroniche delle diverse fasi e mostra le peculiari caratteristiche di ciascuna di esse nell'intorno dell'energia di Fermi. Il sistema esaminato rappresenta un sistema modello per lo studio delle proprietà morfologiche, strutturali ed elettroniche dei film nanostrutturati di TiOx, i quali, grazie al loro elevato rapporto superficie/volume, sono considerati di grande interesse nell'ambito della ricerca su dispositivi per applicazioni fotovoltaiche e di fotocatalisi.
Scanning tunneling microscopy and spectroscopy of titanium oxide nanostructures on the Au(111) surface
MASCARETTI, LUCA
2013/2014
Abstract
This thesis work reports an experimental analysis of TiOx nanostructures and ultrathin films on the Au(111) surface by means of Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The TiOx/Au(111) system is obtained with the electron-beam evaporation technique at low and high coverage, namely 0.3 ML and 1.5 ML of titanium, followed by oxidation. The STM analysis shows the formation of five different TiOx phases, in agreement with previous observations, whose structural and morphological features are discussed thanks to atomically resolved STM images and the results of Low Energy Electron Diffraction (LEED) measurements. The STS analysis, on the other hand, allows to investigate the electronic properties of the TiOx phases and it shows their peculiar individual features around the Fermi energy. The examined system represents a model system for the study of morphological, structural and electronic properties of nanostructured TiOx films, which, thanks to their high surface/volume ratio, are highly regarded in the research on photovoltaic and photocatalytic applications.File | Dimensione | Formato | |
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2014_04_Mascaretti.pdf
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Descrizione: Testo della tesi
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https://hdl.handle.net/10589/92424