A5057048173- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Semiconductor materials and devices
- Molecular Junctions and Nanostructures
- Advanced Materials Characterization Techniques
- Electrocatalysts for Energy Conversion
- Fusion materials and technologies
- Thermal Radiation and Cooling Technologies
- Nanowire Synthesis and Applications
- MXene and MAX Phase Materials
- 2D Materials and Applications
- Electrochemical Analysis and Applications
- Carbon Nanotubes in Composites
- Plasma Diagnostics and Applications
- Photonic Crystals and Applications
- Metal and Thin Film Mechanics
- High-pressure geophysics and materials
- Particle accelerators and beam dynamics
University of California, Los Angeles
2023
University of Bristol
2017-2022
Wide-bandgap semiconductors are exploited in several technological fields such as electron emission devices, energy conversion, high-power high-temperature electronics, and electrocatalysis. Their electronic properties vary significantly depending on the functionalization of surface. Here, we investigated a proof-of-concept modulation one most common wide-bandgap semiconductors, that is, diamonds, to show tunability their by modifying surface termination. Photoelectron spectroscopy was used...
Diamond-based thermionic emission devices could provide a means to produce clean and renewable energy through direct heat-to-electrical conversion. Hindering progress of the technology are output current threshold temperature emitter cathode. In this report, we study effects on caused by in-situ exposure diamond cathode beta radiation. Nitrogen-doped thin films were grown microwave plasma chemical vapour deposition molybdenum substrates. The hydrogen-terminated nano-crystalline was studied...
The Large Plasma Device (LAPD) at UCLA (University of California, Los Angeles) produces an 18 m long, magnetized, quiescent, and uniform plasma a high repetition rate to enable studies fundamental physics. Here, we report on major upgrade the LAPD source that allows for more robust operation significant expansion achievable parameters. original made use heated barium oxide (BaO) coated nickel sheet as electron emitter. This had number drawbacks, including limited range density (≲4.0 × 1012...
Abstract Polycrystalline graphene was transferred onto differently terminated epitaxial layers of boron-doped diamond deposited single crystal substrates. Chemical and electronic characterisation performed using energy-filtered photoemission electron microscopy angle-resolved spectroscopy. Electronic interaction between the observed, where doping on hydrogen oxygen n-doping 250 meV 0 respectively. We found that wide window achievable is effectively determined by surface dipole, easily...
Abstract Material band structures of occupied electronic states are obtainable using conventional angle‐resolved photoemission experiments, leaving the unoccupied far less explored. Here, an alternative approach is built on and expanded to investigate thermalized photoelectrons emitted from crystal surfaces. A model for electron emission constructed reveals material state structure. Potentially applicable any independent secondary generation mechanism, it demonstrated diamond copper...
Thermionic emitting materials are relevant for several technological applications like electron guns, X-ray sources, or thermionic energy converters. As new and surface functionalisations that enable emission developed, it is essential to be able test them in a repeatable reliable manner. Here, we present CO2 laser-heated system tests can used the current of different regardless optical properties form factor. Our reach sample temperatures T ≈ 1000 °C follow pre-programmed heating profiles....
Electrodeposition of Pb on Au has been interest for the variety surface phenomena such as UnderPotential Deposition (UPD) and alloying. Here, we examined interface between electrodeposited film Au, using sensitive techniques X-ray Photoelectron Spectroscopy (XPS), Ultraviolet (UPS), Energy-Filtered Photoemission Electron Microscopy (EF-PEEM) Work Function (WF) mapping. The initially overlayer (~4 ML equivalent thickness) was transferred from electrochemical cell to UHV system. deposited...
A simple first-principles approach is used to estimate the core level shifts observed in X-ray photoelectron spectroscopy for 4f electrons of Hf, Ta, W, and Re; these elements were selected because their levels are relatively close Fermi energy. The first tested by modeling surface low-index surfaces four elemental metals, followed its application well-studied material TaSe2 commensurate charge density wave (CDW) phase, where agreement with experimental data found be good, showing that this...
Abstract An alternative method of doping and surface functionalization diamond using a chemical route was explored. The interaction Li with the bulk oxygen-terminated investigated Angle-Resolved X-ray Photoemission Spectroscopy (ARXPS). A stable LiO 2 termination (100) near-surface achieved up to an annealing temperature 850 °C. changes in between species involved (C, O, Li) their stoichiometric ratios at were as function temperature. This done ARXPS peak analysis. Graphic abstract
The large-scale formation of patterned, quasi-freestanding graphene structures supported on a dielectric has so far been limited by the need to transfer onto suitable substrate and contamination from associated processing steps. We report μm scale, few-layer formed at moderate temperatures (600–700 °C) directly an interfacial oxidizing Si layers graphene/substrate interface. show that thickness this underlying support can be tailored further additional intercalation prior oxidation. This...