Electronic Properties of Metal Oxide Films Studied by Core Level Spectroscopy

In this particular dissertation core level electron spectroscopy has been accustomed to study various areas of metal oxide films grown under ultra-high vacuum conditions.Studies on in situ ion insertion of lithium into thin TiO2 systems were performed. The electronic and geometric properties are investigated in depth, as well as an estimation of demand transfer from Li to Ti. A comprehensive study of chemical vapour deposition of ZrO2 on Si(100)-(2×1) was performed. ZrO2 is positioned to be an insulator, i.e. its electronic levels are decoupled from the substrate and the Zr stages are the best referenced for the local vacuum level. The alignment to the valence and conduction band has been determined.Combinatorial chemical vapour deposition of TiO2 and ZrO2 on Si(100)-(2×1) was noticed. A movie with graded stoichiometry composed of pure TiO2 and ZrO2 on the opposing ends and mixed composition of both oxides in the centre was obtained. A comprehensive study on the electronic levels said that ZrO2 remains an insulator in the monolayer regime and that alteration of ZrO2 with a tiny amount of TiO2 creates a more symmetric alignment to the bands compared to Si.

Contents: Electronic Properties of Metal Oxide Films Studied by Core Level Spectroscopy

Introduction
1 Fundamental concepts
1.1 Light and synchrotron radiation
1.2 Matter and electronic structure
1.2.1 Some information about the electronic structure of solids
1.3 Photon-electron interaction
1.4 In situ and ex situ
1.5 Ultra-high vacuum (UHV)
2 Film preparation
2.1 In situ chemical vapour deposition (CVD)
2.1.1 Combinatorial CVD
2.2 In situ vapour exposure (lithium insertion)
2.3 Ex situ preparation techniques
2.3.1 Sol-gel preparation
2.3.2 Electrochemical preparation
2.3.3 Electrodeposition
3 Characterisation techniques
3.1 Core level electron spectroscopy
3.2 Photoelectron spectroscopy (PES/XPS)
3.2.1 Determination of the work function
3.2.2 Chemical shifts
3.2.4 PES line shape
3.3 Surface sensitivity and depth distribution
3.3.1 Determination of film thickness
3.4 X-ray absorption spectroscopy (XAS)
3.4.1 Crystal field splitting
3.4.2 XAS delineation process
3.5 X-ray magnetic circular dichroism (XMCD)
3.5.1 The XMCD sum rules
3.6 Core hole decay processes
3.7 Resonant photoelectron spectroscopy (RPES)
3.8 Theoretical approach: DFT
4 Summary of the results
4.1 Lithium insertion into TiO2 systems (Papers I-III)
4.1.1 Common effects of lithium insertion
4.1.2 Paper I: Electronic Structure of ultra-high Vacuum Lithium inserted anatase TiO2
4.1.3 Paper II: Phase Separation and Charge Localisation in UHV lithiated anatase TiO2 Nanoparticles
4.1.4 Paper III: Li insertion in sol-gel prepared Mn doped TiO2 studied by electron spectroscopy under ultra-high vacuum conditions
4.2 Core hole effects in XAS
4.2.1 Paper IV: Threshold effects in the O 1s x-ray absorption spectrum of TiO2
4.3 Investigation of UHV-CVD deposited ZrO2 on Si
4.3.1 Paper V: Ultra-high vacuum metal organic chemical vapor deposition of ultrathin ZrO2 films on Si(100) and Si(111) studied by electron spectroscopy
4.3.2 Paper VI: Growth of ultrathin ZrO2 films on Si(100): Film-thickness-dependent band alignment
4.3.3 Paper VII: Band alignment at the ZrO2/Si(100) interface studied
by photoelectron and x-ray absorption spectroscopy
4.3.4 Paper VIII: Combinatorial chemical vapour deposition of an ultrathin ZrO2-TiO2 film on Si(100)-(2×1) in ultra-high vacuum
4.4 Magnetism
4.4.1 Paper IX: Electronic structure investigation of (Zn,Co)O room
temperature ferromagnets
temperature ferromagnets….