A5009006442- Transition Metal Oxide Nanomaterials
- Electronic and Structural Properties of Oxides
- ZnO doping and properties
- Iron oxide chemistry and applications
- Topological Materials and Phenomena
- Semiconductor materials and devices
- Advanced Memory and Neural Computing
- Graphene research and applications
- Surface and Thin Film Phenomena
- Catalytic Processes in Materials Science
- Magnetic Properties and Synthesis of Ferrites
- Electrocatalysts for Energy Conversion
- Gas Sensing Nanomaterials and Sensors
- Physics of Superconductivity and Magnetism
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Neural Networks and Reservoir Computing
- Ga2O3 and related materials
- Nonlinear Photonic Systems
- Mine drainage and remediation techniques
- Mechanical and Optical Resonators
- 2D Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Magnetic properties of thin films
- Catalysis and Hydrodesulfurization Studies
Trinity College Dublin
2016-2024
The ability of VO2 to undergo semiconductor-to-metal phase transition (SMT) upon heating makes it a very attractive material for uncooled bolometers. SMT represents large temperature coefficient resistance, which is an important parameter the development highly responsive microbolometers. However, other characteristics such as its high (341.2 K), sharpness transition, hysteresis, and room resistivity limit performance this in In work, we grow high-quality epitaxial ultrathin film on c-plane...
Abstract Titanium (Ti)-doped hematite (α-Fe 2 O 3 ) films were grown in oxygen-depleted condition by using the spray pyrolysis technique. The impact of post-deposition annealing oxygen-rich on both conductivity and water splitting efficiency was investigated. X-ray diffraction pattern revealed that are rhombohedral α-Fe structure dominantly directed along (012). as-grown found to be highly conductive with electrons as majority charge carriers (n-type), a carrier concentration 1.09×10 20 cm...
Abstract High-quality epitaxial p-type V 2 O 3 thin films have been synthesized by spray pyrolysis. The exhibited excellent electrical performance, with measurable mobility and high carrier concentration. conductivity of the varied between 115 1079 Scm −1 while optical transparency ranged from 32 to 65% in visible region. observed limitations thinner films’ were attributed nanosized granular structure presence two preferred growth orientations. 60 nm thick film demonstrated a highly...
Abstract NbO terminated Nb(110) and its oxidation are examined by scanning tunneling microscopy spectroscopy (STS). The oxide structures strongly influenced the structural electronic properties of underlying substrate. is one-dimensional few-nanometer nanocrystals, which form an ordered pattern. High-resolution STS measurements reveal that nanocrystals regions between exhibit different characters. Low-dosage oxidation, sufficient for sub-monolayer coverage NbO, with subsequent UHV annealing...
Abstract In this work we present a comprehensive study of the domain structure nickel oxide single crystal grown by floating zone melting and suggest correlation between point defects observed structure. The properties domains dictate dynamics resistive switching, water splitting gas sensing, to name but few. Investigating can provide deeper understanding their formation structure, which potentially allows one tailor aforementioned applications. A range inhomogeneities are diffraction...
We investigate the origin of variation in resistive switching hysteresis VO2 thin films. Using pulsed electrical measurements textured film devices, we show that observed I–V curves results from Joule heating effects, particularly low-resistance state. The is reduced by increasing cooling time between pulses. Based on a mechanism heating-induced metal-insulator transition, numerical simulations are performed, which agree with experimental hysteresis. Finally, framework for engineering...
Renewed interest in the ferroelectric semiconductor germanium telluride was recently triggered by direct observation of a giant Rashba effect and 30-year-old dream about functional spin field-effect transistor. In this respect, all-electrical control texture material combination with properties at nanoscale would create advanced functionalities spintronics data information processing. Here, we investigate atomic electronic GeTe bulk single crystals their (111) surfaces. We succeeded growing...
Significant advancements have been made in the past few decades precise control of VO2 synthesis, enabling creation structures with diverse morphologies and distinct phase transition properties. Existing synthesis methods used research settings are often inadequate for large-scale production, particularly concerning high-quality thin films. Addressing these obstacles is crucial to unlocking full potential harnessing its multifunctional properties a broad range practical applications. In this...
The mechanism of few-layer graphene growth on the technologically relevant cubic-SiC/Si(001) substrate is uncovered using high-resolution core-level and angle-resolved photoelectron spectroscopy, low-energy electron microscopy, microspot diffraction. thickness graphitic overlayer supported silicon carbide related changes in surface structure are precisely controlled by monitoring progress graphitization situ during high-temperature synthesis, a combination microspectroscopic techniques....
Scanning tunneling microscopy (STM) measurements of the (110) surface magnetite showed coexistence two reconstructions: known $(1\ifmmode\times\else\texttimes\fi{}3)$ row reconstruction and a surprising atomic structure high complexity which occupies small fraction surface. Oxygen vacancies on ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$(110) B-terminated have previously been determined to be most energetically favorable termination those considered [Li et al., Surf. Sci. 601, 876 (2007)]. However,...
The niobium surface is almost always covered by a native oxide layer which greatly influences the performance of superconducting devices. Here we investigate highly stable overlayer Nb(110), characterized its distinctive nanocrystal structure as observed scanning tunneling microscopy (STM). Our ab initio density functional theory (DFT) calculations show that subtle reconstruction in atoms gives rise to rows fourfold coordinated oxygen separated regions threefold oxygen. are determined be...
Sb is a three-dimensional Peierls insulator. The instability gives rise to doubling of the translational period along [111] direction and alternating van der Waals covalent bonding between (111) atomic planes. At surface Sb, condition violated, which in theory can give properties differing from bulk. electronic structure have been simulated by density functional calculations. We considered two possible surfaces, containing dangling bonds or bonds. In models, surfaces are infinite defect...
Defects introduced to the surface of Bi(111) break translational symmetry and modify states locally. We present a theoretical experimental study 2D defects on that they induce. Bi crystals cleaved in ultrahigh vacuum (UHV) at low temperature (110 K) resulting ion-etched are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy, ultraviolet spectroscopy (UPS), scanning tunneling microscopy (STM) as well (STS) techniques combination with density functional...
Herein, we report a simple method for covalent modification of surface supported graphene with photoactive dyes. Graphene was fabricated on cubic-SiC/Si(001) wafers due to their low cost and suitability mass-production continuous fit electronic applications millimetre scale. Functionalisation the carried out in solution via white light induced photochemical generation phenazine radicals from diazonium salt. The resulting covalently bonded phenazine-graphene hybrid structure characterised by...
The strongly correlated electron material, vanadium dioxide (VO2), has seen considerable attention and research application in metal-oxide electronics due to its metal-to-insulator transition close room temperature. Vacuum annealing a V2O5(010) single crystal results Wadsley phases (VnO2n+1, n > 1) VO2. resistance changes by factor of 20 at 342 K, corresponding the phase Macroscopic voltage-current measurements with probe separation on millimetre scale result Joule heating-induced...
In this work we investigate the SrTiO 3 (110) surface by reflectance anisotropy spectroscopy (RAS) at varying preparation steps including ex situ wet etching, high temperature oxygen annealing, as well in vacuum annealing. Different terminations show distinctly different RAS spectra which are correlated to an altered stoichiometry measured X‐ray photoelectron (XPS) and valence band structure UV‐photoelectron (UPS) cases of conductive samples. We link changes observed various reconstructions,...
We present a study of (110)-terminated magnetite using range surface-sensitive techniques, the foremost those being reflectance anisotropy spectroscopy (RAS). The anisotropic optical response as-polished and row-reconstructed terminations are investigated. responses interpreted to result from termination-induced shifts in energy bulklike transitions. Density functional theory (DFT) calculations demonstrate that row reconstruction ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$(110) exhibits strain its...
The growth of Fe nanostructures on the stoichiometric MoO2/Mo(110) and oxygen-rich MoO2+x /Mo(110) surfaces has been studied using low-temperature scanning tunnelling microscopy (STM) density functional theory calculations. STM results indicate that at low coverage nucleates surface, forming small, well-ordered nanoclusters uniform size, each consisting five atoms. These five-atom clusters can agglomerate into larger reflecting substrate geometry, but they retain their individual character...
Abstract Oxygen adatoms on the MoO 2+ x /Mo(110) surface are observed to be removed when a sufficiently large bias is applied between scanning tunneling microscope tip and surface. Experimental observations, such as polarity dependence of adatom removal observation an intermediate state, indicate that penetrates oxide layer. Through comparison finite element method simulations with various experimental relationships, electric field concluded sole contributor penetration into The energetic...