Professor David Carey

1. Graphene and Beyond Graphene: 2D Layered Materials, band gap engineering, doping and characterisation

• Molecular doping of graphene to enhance the high frequency conductivity from DC, through GHz to THz and published in ACS Applied Materials and Interfaces.
• Structural characterisation and electron-phonon matrix element calculations in planar and buckled silicene and germanene monolayers published in ACS Applied Materials and Interfaces.
• DFT calculations of molecular doping of bilayer graphene, ACS Nano, where we show how to open an electrical band gap of up to 150 meV in AB stacked BLG using molecular dopants.
• Electrical and Raman characterisation of low substrate temperature (415oC) photothermal chemical vapour deposition of graphene on Cu. Using an optical source it is possible to efficiently couple energy into the metal catalyst growth surface while the substrate is held at over 250oC lower in temperature.

2. Metallic nanoparticles for high frequency electronics and antennas: We have shown, published in ACS Applied Materials, that the high frequency (up to 220 GHz) electrical losses of screen printed mm-long coplanar waveguide structures of metallic silver nanoparticles are lower than that of conventional thick-film paste micron-sized silver grains due to the better packing and the smoother surface. The use of metallic nanoparticles in this way may offer a route to efficient, flexible conformal antennas.

3. Carbon Nanotube Science and Engineering:

• Recent studies of the production of high density forests of carbon nanotubes for interconnects vias grown on conductive TiN substates.
• In collaboration with the UK's National Physical Laboratory, we have been looking at cavitation effects in the dispersion and controlled length reduction of nanotubes. In this study, published in J. Phys. Chem. B, we distinguish between stable cavitation, which leads to chemical modification of the surface of the CNTs, and inertial cavitation, which favours CNT exfoliation and length reduction. Efficient dispersion of CNTs in aqueous solution is found to be dominated by mechanical forces generated via inertial cavitation, which in turn depends critically on surfactant concentration.

4. Quantum Technology based on Rare Earth Ions in Silicon: The first study of Er3+ centres in oxygen co-implanted Si and the identification of the monoclinic symmetry defect centre and how O and F co-implantation affected the ESR and photoluminescence properties in Si. This work was followed up by an examination of the validity of the cubic crystal field approximation for trigonal and tetragonal symmetry erbium 3+ centres.

PhD positions are available to highly qualified candidates in all of the above areas, especially in 2D materials, DFT, condensed matter physics or solid state electronics.

PhD research positions

For a PhD position you will normally require a good Honours degree or MSc in Electronic Engineering, Physics or Materials. Current PhD positions include

1. Graphene and graphene electronics : This project will use ab initio density functional theory to examine the electronic properties of graphene and related materials such as bilayer graphene in the presence of atoms and molecules. The project will examine how adsorption induces changes the carrier concentration (doping) of graphene and identify donor or acceptor behaviour; how the electronic and optical band gap depends on the type of species adsorbed and their concentration and how the electronic properties such band structure, density of states and transport properties change with adsorption.

2. Electronic and Structural Properties of 2D Nanomaterials: This project will use ab initio density functional theory to examine the electronic properties of 2D layered materials such as graphene, silicene, germanene, stanene and MoS2 and related materials. The project will calculate the electronic properties such band structure and the density of states and how they will change adsorption. The project will also examine the interaction between electrons and phonons in these materials.

See PhD project list here for more information. Both experimental and theoretical projects in the areas of graphene, bilayer graphene and other layered materials; high field and high frequency characterization of nanomaterials.