subject:(Angle resolved XPS)

1. G. Drera. ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES.

Degree: 2012, Università degli Studi di Milano

URL: http://hdl.handle.net/2434/168728

► The scope of this Thesis is the study of the electronic structure of two Ti-based oxide systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO)… (more)

▼ The scope of this Thesis is the study of the electronic structure of two Ti-based oxide systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO) heterojunctions, which display remarkable physical phenomena, so far not completely understood. In both cases, the titanium-related electronic states are expected to play a fundamental role and thus have been probed by means of X-ray photoemission spectroscopies. A weak room-temperature ferromagnetism (FM) has been recently detected in slightly reduced TiO2 thin film and in other oxides, such as HfO2 and CaO; since these materials are insulating closed-shell systems, this phenomenon has been classified as "d0 magnetism". Magnetism in these compounds seems to be related to the growth methodology and ultimately to the presence of structural defects, such as oxygen vacancies. Therefore, a thorough analysis of titanium electronic states, and especially of the defect-related Ti3+ energy levels, is needed in order to understand the origin of magnetic interactions. In the first part of this Thesis, a comprehensive magnetic characterization of a set of TiO2 samples is given, together with the analysis of Ti 3d-related states carried out with X-ray photoemission (XPS) and resonant photoemission (ResPES). A set of N-doped TiO2 thin films have also been grown, in order to verify the effect of doping on the TiO2 magnetism. The hypothesis of a clustered oxygen-vacancies origin of FM is then discussed in the light of the experimental and theoretical results. Another interesting oxide system in which the stoichiometry of Ti ions play a fundamental role is the LAO-STO interface. LAO and STO, separately, are two band insulators, with an empty shell electronic structure (3d0 for STO, 4f0 for LAO) and a similar perovskite structure; however, the interface created by growing LAO on the top of STO (001) has found to become metallic, hosting a 2D electron gas. This heterostructure becomes conductive only when the STO is terminated with a TiO2 layer; therefore, the Ti-related electronic states are expected to host the metallic states. The second part of this Thesis is devoted to the study of conductive and insulating LAO-STO interfaces, carried out by XPS, X-ray absorption (XAS) and with ResPES techniques. The stoichiometry of each atomic species has been evaluated through a comparison with LAO and STO single crystals. A resonance enhancement of the conductive Ti states, associated to a small fraction of Ti3+ ions is reported and compared to theoretical calculations. On the basis of these results, the origin of metallic states in ultra-thin LAO-STO interfaces is properly addressed. In addition, a characterization of the intermixing and the disorder at the LAO-STO interface has been done through angle-resolved XPS, providing important information on the intermixing of light cations (Al, Ti) otherwise missed by X-ray diffraction techniques. Advisors/Committee Members: tutor: L. Sangaletti, coordinatore: M. Bersanelli, BERSANELLI, MARCO RINALDO FEDELE.

Subjects/Keywords: titanium oxides; magnetic oxide; LAO-STO; LaAlO3; SrTiO3; perowskite heterojunction; x-ray photoemission spectroscopy; resonant photoemission; angle resolved XPS; Settore FIS/03 - Fisica della Materia

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Drera, G. (2012). ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES. (Thesis). Università degli Studi di Milano. Retrieved from http://hdl.handle.net/2434/168728

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Drera, G.. “ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES.” 2012. Thesis, Università degli Studi di Milano. Accessed January 20, 2021. http://hdl.handle.net/2434/168728.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Drera, G.. “ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES.” 2012. Web. 20 Jan 2021.

Vancouver:

Drera G. ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES. [Internet] [Thesis]. Università degli Studi di Milano; 2012. [cited 2021 Jan 20]. Available from: http://hdl.handle.net/2434/168728.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Drera G. ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES. [Thesis]. Università degli Studi di Milano; 2012. Available from: http://hdl.handle.net/2434/168728

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. G. Salvinelli. PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES.

Degree: 2015, Università degli Studi di Milano

URL: http://hdl.handle.net/2434/262157

► In the recent years, electronic devices have become smaller and faster, as well as more powerful and efficient. However, the size of the building blocks… (more)

▼ In the recent years, electronic devices have become smaller and faster, as well as more powerful and efficient. However, the size of the building blocks of the current electronics - i.e. the transistors - is quickly approaching the limits of manufacture. The need of a new generation of devices based on novel mechanisms is today essential. In this scenario, well-defined interfaces between oxide materials have produced novel electronic systems displaying a spectacular variety of properties with promising potentialities for future devices, such as colossal magnetoresistance, high-temperature superconductivity, magnetism at the interface between non magnetic oxides, as well as two-dimensional electron gas between two oxide insulators. Indeed, interfaces between perovskite oxides - e.g. the LaAlO3/SrTiO3 – have shown properties at the nanometer scale that are qualitatively different from their single building blocks, allowing one to engineer novel functionalities through the growth of epitaxial heterostructures. Nevertheless, both atomic and electronic reconstructions could be present in oxide interfaces when a polar discontinuity occurs at the junction and the possibility to probe non-destructively the cation depth profiles can provide further insight into the oxide heterointerface physics. This is also true for less-ordered systems - i.e. amorphous thin films - which are playing a key role in the development of new architectures in photovoltaic applications, such as the CdxSnyOz/TiO2 heterojunction. In this Thesis, the combination of chemical and structural information on a local scale (i.e. at the interface and the nearby few atomic layers) has been obtained by combining an effective modeling of angle-resolved x-ray photoemission data, with synchrotron based electron spectroscopy techniques. It is shown how in oxides the interfacial electronic properties can be driven by complex substitutional effects across the interface, such as stoichiometry gradients, cation vacancies and interdiffusion, as well as by the presence of interfacial/surface oxygen vacancies. Advisors/Committee Members: tutor: L. Sangaletti, coordinatore: M.Bersanelli, BERSANELLI, MARCO RINALDO FEDELE.

Subjects/Keywords: photoemission; angle-resolved XPS; resonant photoemission; band alignment; interdiffusion; stoichiometry gradient; band offset; LaAlO3/SrTiO3; solar cell; DSSC; front contact; blocking layer; buried interface; Settore FIS/03 - Fisica della Materia

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Salvinelli, G. (2015). PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES. (Thesis). Università degli Studi di Milano. Retrieved from http://hdl.handle.net/2434/262157

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Salvinelli, G.. “PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES.” 2015. Thesis, Università degli Studi di Milano. Accessed January 20, 2021. http://hdl.handle.net/2434/262157.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Salvinelli, G.. “PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES.” 2015. Web. 20 Jan 2021.

Vancouver:

Salvinelli G. PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES. [Internet] [Thesis]. Università degli Studi di Milano; 2015. [cited 2021 Jan 20]. Available from: http://hdl.handle.net/2434/262157.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Salvinelli G. PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES. [Thesis]. Università degli Studi di Milano; 2015. Available from: http://hdl.handle.net/2434/262157

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Georgia Tech

3. Diao, Jie. Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

URL: http://hdl.handle.net/1853/7628

► This thesis is devoted to development of techniques to quantify chemical and mechanical influences during chemical mechanical polishing (CMP) near the surface of a polymer… (more)

Subjects/Keywords: Chemical mechanical polishing; Depth profile; Polymers; Optical properties; Angle resolved XPS

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Diao, J. (2004). Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/7628

Chicago Manual of Style (16^th Edition):

Diao, Jie. “Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.” 2004. Doctoral Dissertation, Georgia Tech. Accessed January 20, 2021. http://hdl.handle.net/1853/7628.

MLA Handbook (7^th Edition):

Diao, Jie. “Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.” 2004. Web. 20 Jan 2021.

Vancouver:

Diao J. Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Jan 20]. Available from: http://hdl.handle.net/1853/7628.

Council of Science Editors:

Diao J. Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/7628

Georgia Tech

4. Myneni, Satyanarayana. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

URL: http://hdl.handle.net/1853/7605

► As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several… (more)

▼ As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several challenges. A cleaning process should be environmentally benign, compatible with dielectric materials and copper, and provide residue removal from narrow and high aspect ratio features. In this work, sub-critical CO2 based mixtures have been developed to remove the etch residues; these mixtures satisfy the above requirements and can potentially replace the two step residue removal process currently used in the integrated circuit (IC) industry. Based on the chemical nature of the residue being removed, additives or co-solvents to CO2 have been identified that can remove the residues without damaging the dielectric layers. Using the phase behavior of these additives as a guide, the composition of the co-solvent was altered to achieve a single liquid phase at moderate pressures without compromising cleaning ability. The extent of residue removal has been analyzed primarily by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Various techniques such as attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy, angle-resolved XPS (ARXPS), and interferometry were used to probe the interaction of cleaning fluids with residues. Model films of photoresists and plasma deposited residues were used to assist in understanding the mechanism of residue removal. From these studies, it was concluded that residue removal takes place primarily by attack of the interface between the residue and the substrate; a solvent rinse then lifts these residues from the wafer. It has been shown that transport of the additives to the interface is enhanced in the presence of CO2. From positronium annihilation lifetime spectroscopy (PALS) studies on a porous dielectric film, it has been shown that these high pressure fluids do not cause significant changes to the pore sizes or the bonding structure of the film. Hence, this method can be used to remove post etch residues from low-k dielectric films. Advisors/Committee Members: Dr. Dennis W. Hess (Committee Chair), Dr. Amyn S. Teja (Committee Member), Dr. Charles A. Eckert (Committee Member), Dr. Charles L. Liotta (Committee Member), Dr. J. Carson Meredith (Committee Member).

Subjects/Keywords: Low-K; Angle resolved XPS; Surface cleaning; Supercritical carbon dioxide; ATR-FTIR; Fluorocarbon residue; Etch residue; Semiconductors Cleaning; Plasma etching; Liquid carbon dioxide Industrial applications

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Myneni, S. (2004). Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/7605

Chicago Manual of Style (16^th Edition):

Myneni, Satyanarayana. “Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.” 2004. Doctoral Dissertation, Georgia Tech. Accessed January 20, 2021. http://hdl.handle.net/1853/7605.

MLA Handbook (7^th Edition):

Myneni, Satyanarayana. “Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.” 2004. Web. 20 Jan 2021.

Vancouver:

Myneni S. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Jan 20]. Available from: http://hdl.handle.net/1853/7605.

Council of Science Editors:

Myneni S. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/7605

University of Illinois – Urbana-Champaign

5. Mohapatra, Chandra. Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy.

Degree: PhD, 0240, 2012, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/31913

► Growing macroscopic graphene ﬁlms with the aim of making graphene commerically viable is being researched a lot recently. Although graphene isolated by exfoliation of Highly… (more)

▼ Growing macroscopic graphene ﬁlms with the aim of making graphene commerically viable is being researched a lot recently. Although graphene isolated by exfoliation of Highly Oriented Pyrolytic Graphite (HOPG) crystals has been in place for sometime now, its micro sample size has triggered the research to produce wafer-scale graphene ﬁlms. Chemical Vapor Deposition (CVD) of graphene on metallic substrates and thermal decomposition of SiC are two such eﬀorts in the direction of producing wafer-scale graphene ﬁlms but none of these techniques are full-proof. While CVD graphene needs to be transferred from a metallic substrate to an insulating one for device applications, graphene synthesized through thermal decomposition relies so much on the rate of Silicon (Si) sublimation that getting a uniform graphene coverage remains a challenge. In this dissertation, I attempt to grow epitaxial graphene by Molecular Beam Epitaxy (MBE) by depositing Carbon (C) from a high purity solid graphite source where the growth rate of graphene, the rate of deposition and the substrate temperature can be controlled independently. In this research work, I studied the growth of graphene on two substrates with hexagonal symmetry: c-plane sapphire and 4H-SiC (000¯ 1). Both these substrates are decently lattice matched to graphene. The dynamics of the growth process which is dependent on the substrate used is studied in detail. It will be reported that in both the substrates, the growth starts in an epitaxial manner and progresses to being polycrystalline with increase of thickness. The MBE grown ﬁlms are systematically analyzed with in-situ RHEED, ex-situ XPS, AFM, Raman Spectroscopy and Electrical Transport. Clear evidence of tensile stress is seen in the AFM and Raman studies in the graphene ﬁlms grown on c-plane sapphire. Whereas, Raman studies conﬁrm the presence of compressive stress in the graphene ﬁlms grown on 4H-SiC (000¯ 1) where the mismatch of the coeﬃcient of thermal expansion (CTE) plays an important role. Raman studies show a clear evidence of the defect peak (D) in all the ﬁlms grown on c-plane sapphire no matter how smooth the morphology is. However, the D peak is absent in very thin epitaxial graphene grown on 4H-SiC (000¯ 1) substrates. The symmetrical nature of the 2D peak in the Raman studies of multi-layered graphene ﬁlms grown on both c-plane sapphire and 4H-SiC (000¯ 1) indicate the presence of random stacking order. Electrical transport in both the classes of graphene ﬁlms shows a non-metallic behavior: power law behavior in the high temperature regime and a generalized Variable Range Hopping (VRH) type behavior at low temperatures. The low temperature transport of graphene grown on c-plane sapphire will be shown to be an interplay of both 2D and 3D Mott VRH. Whereas, Efros Shklovskii VRH plays a dominant role in the low temperature transport of graphene grown on 4H-SiC (000¯ 1). With all these ﬁndings in mind, some potential solutions are proposed which would take this research forward. Advisors/Committee Members: Eckstein, James N. (advisor), Mason, Nadya (Committee Chair), Eckstein, James N. (committee member), Vishveshwara, Smitha (committee member), Stack, John D. (committee member).

Subjects/Keywords: Highly Oriented Pyrolytic Graphite (HOPG); Molecular Beam Epitaxy (MBE); Mono Layer (ML); Chemical Vapor Deposition (CVD); Quartz Crystal Monitor (QCM); Reﬂection High Energy Electron Diﬀraction (RHEED); Atomic Force Microscopy (AFM); X-ray Photoelectron Spectroscopy (XPS); Auger Electron Spectroscopy (AES); Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS); Variable Range Hopping (VRH); Weak Localization (WL); Coeﬃcient of Thermal Expansion (CTE); Polymethyl Methacrylate (PMMA); Polyethylene Terephthalate (PET); Pyrolytic Boron Nitride (PBN); Frederick Seitz Material Research Laboratory (MRL); Center for Microanalysis and Materials (CMM); Isopropyl Alcohol (IPA); Trichloro Ethylene (TCE); Ultra High Vacuum (UHV); Scanning Tunneling Microscopy (STM ); Low Energy Electron Diﬀraction (LEED); Full width at Half Maximum (FWHM); Bilayer Pseudo Spin Field Eﬀect Transistor (BiSFET); Field Effect Transistor (FET); Chemical Mechanical Polished (CMP)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Mohapatra, C. (2012). Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/31913

Chicago Manual of Style (16^th Edition):

Mohapatra, Chandra. “Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy.” 2012. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed January 20, 2021. http://hdl.handle.net/2142/31913.

MLA Handbook (7^th Edition):

Mohapatra, Chandra. “Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy.” 2012. Web. 20 Jan 2021.

Vancouver:

Mohapatra C. Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2012. [cited 2021 Jan 20]. Available from: http://hdl.handle.net/2142/31913.

Council of Science Editors:

Mohapatra C. Growth and characterization of epitaxial graphene films by Molecular Beam Epitaxy. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2012. Available from: http://hdl.handle.net/2142/31913

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