Prerequisites
A knowledge of solid state physics and particel physics at a Part II level.
Learning Outcomes and Assessment
You will learn how reducing device dimensions can change the properties of solid-state systems and how transport is impacted by sample dimensionality and how magnetic fields can also change the dimensionality. You will be able to estimate how size and magnetic fields impact transport properties. The low temperature quantum properties of devices in two dimensional, one dimensional and quantum dot systems will be explored in experiments and how single electrons can be trapped and their spin state remotely measured. A brief introduction to spin QUBITs and quantum computation in solid state using spins will be taught.
The spin properties of devices will be introduced including magnetism and spintronic devices where the spin state of the electron is utilized instead of the charge.
How optical diodes alter as the dimension is reduced will also be taught and you will learn how light emission and absorption is altered by changing the confinement dimensions. The optical properties of two-dimensional, one-dimensional and quantum dot diodes will be explained. Single and two proton sources will be discussed.
Finally, we will explore how graphene, nano-wires and molecules can also be used to make electronic and optical devices.
You should be able to estimate the physical measurable parameters for all the above systems by the end of the course.
Synopsis
Introduction to low dimensional systems: length and energy scales, overview of fabrication techniques and possibilities, applications of low-dimensional physics, examples, top-down vs bottom-up.
Electronic properties in low-dimensional systems: band engineering; heterostructures, 2D electron gas.
Ballistic motion, collimation, experiments.
Quantum transport in 1D wires: eigenstates, conductance, saddle-point potential, d.c. bias.
Electrons in high magnetic fields: Hall effects, Landau levels, oscillation of the Fermi energy. Landauer-Büttiker formalism, integer quantum Hall effect, edge states.
Electron-electron interactions, quasiparticles. Fractional quantum Hall effect, composite fermions.
Transport through 0D quantum dots, Coulomb blockade, resonant tunnelling, charge detection, single-electron dots, artificial atoms, antidots. Surface-acoustic-wave current source.
Optical properties. Optical transitions, excitons. Semiconductor lasers as example of effects of confinement. S-K growth, self-assembled quantum dots, microcavities, coupled modes. Single and entangled photon sources for quantum cryptography.
Spintronics: Giant magnetoresistance (briefly), tunnelling magnetoresistance (spin-valve) in layered structures. Spin injection from a ferromagnet to a semiconductor.
Quantum computation (briefly). Spin in a quantum dot as a qubit for quantum computation. Detection and manipulation of single spins – charge-to-spin conversion, electron spin resonance.
Molecular systems. Self-assembly. Conjugated polymers – electronic structure and devices. Transport in carbon nanotubes and graphene. Single-molecule transport. Nanocrystals, nanorods.
BOOKS
A comprehensive set of notes will be given out. No book covers the whole course. Background material may be found in semiconductor textbooks such as Kittel, and Ashcroft and Mermin.