Department of Physics, Unit Catalogue 2011/12
|Level:||Masters UG & PG (FHEQ level 7)|
|Supplementary Assessment:||Like-for-like reassessment (where allowed by programme regulations)|
|Requisites:||Before taking this unit you must take PH30030|
The aims of this unit are to outline properties of materials at the nanoscale, to describe methods for the fabrication, visualisation and probing of nanostructures, and to give some examples of their possible applications. Overall, the aims are to give an introduction to representative topics of Nanoscience and Nanotechnology as a modern discipline.
After taking this unit the student should be able to:
* demonstrate a thorough understanding of the impact of the nanoscale on the electronic structure, charge-transport and magnetic properties of materials;
* describe the basic properties of quasi-1D and 0D systems;
* give a detailed explanation of the physical principles of single-molecule devices;
* describe, explain, critically analyse and compare techniques for probing the nanoscale directly, with sub-nanometer resolution, using scanning probe microscopies;
* apply taught formalisms to the analysis of quantum/physical phenomena that arise at the nanoscale, i.e. the "physics under the microscope's tip", and solve representative problems in the field;
* describe, explain and derive representative properties of topical nanoscale nanomaterials, such as graphene and carbon nanotubes;
* describe and critically assess the merits and limitations of "top-down" and "bottom-up" nanofabrication techniques, and their capabilities;
* articulate public concerns and the benefits of nanoscience and nanotechnology.
Numeracy T/F A, Problem Solving T/F A.
Nanotechnology - what is it? (1 hour): Advantages, prospective applications and potential impact.
Impact of the nanoscale on physical properties (1 hour): Classical scaling laws. Breakdown of scaling laws at the nanoscale. Atomic clusters. Magnetic properties of nanoparticles. Superparamagnetism.
Quasi-1D systems (4 hours): Electronic structure of 2D, quasi-1D and 1D systems. Subbands and transverse modes. Electrical transport in quasi-1D conductors. Ballistic and diffusive transport. Conductance quantisation and the Landauer formula. Interface resistance and Ohm's law. Büttiker-Landauer formalism. Effect of temperature on nanoscale conductance.
0D systems (3 hours): Electronic structure of 0-D systems. Quantised energy levels. Electrical transport in 0-D. Tunnelling through a potential barrier. Coulomb blockade. Weak and strong coupling to electrodes. Single-electron transistor. Co-tunnelling. Shuttling of electrons.
Molecular systems (3 hours): Molecular orbitals. HOMO and LUMO states. Mechanisms of charge transport. Metal-molecule-metal junctions. Role of electrodes. Cases of weak and strong coupling. Single-level model. Energy diagrams and potential profiles. Single-molecule transistor. Single-molecule magnets: blocking temperature and tunnelling of the magnetic moment.
Probing and manipulation at the nanoscale (6 hours):
1. Scanning Tunneling Microscopy (STM) and associated Quantum Phenomena: STM principles, formalisms and challenges. Imaging and Spectroscopy: link to electronic structure. Inelastic tunnelling. Spin-Polarised STM. STM manipulation of atoms and molecules. Electron confinement. Quantum Corals. Investigations of topical nanomaterials: graphene, carbon nanotubes and molecular systems.
2. Atomic Force Microscopy (AFM) and Forces at the nanoscale: Nature & magnitude of forces at the nanoscale. AFM principles and realization; Force Detection schemes. Scanning modes in AFM: contact, tapping and non-contact. Atomic resolution with AFM, measurement of interatomic/intermolecular forces and bonding energies. Applications of AFM (chemical, electrical, magnetic) in material and life sciences.
Nanomaterials (3 hours):
1.Graphene: Optical Identification. Bonding and Electronic structure. 2D density of states. Transition towards graphite. Stability and Rippling. Confinement effects in nanoribbons. Minimum conductivity/carrier puddles.
2. Carbon Nanotubes: Topology of Single-WWalled Carbon Nanotubes (SWCNTs). Quantization. Band structure. Semiconducting / Metallic SWCNTs. Density of states. Applications: Photoluminescence. Ballistic conductors. Field-effect transistors (comparison with graphene).
Nanofabrication techniques (1 hour): Types of nanostructures. 'Bottom-up' and 'top-down' approaches to nanotechnology. "Top down" techniques: photolithography, e-beam lithography, focused ion beam lithography. "Bottom-up" methods: Self-Assembly: principles, mechanisms and forces, applications.
PH40085 is Compulsory on the following programmes:Department of Physics
PH40085 is Optional on the following programmes:Programmes in Natural Sciences