Spring Semester

Unit(s) of Assessment	Weighting Towards Module Mark( %)
Written Closed Book Examination (2 hours)	80
Assignment	20
Qualifying Condition(s)  A weighted aggregate mark of 50% is required to pass this module.

This module is concerned with the operation of advanced nanoscale electronic devices. Fundamental issues about device performance will also be addressed as will aspects of device processing. Spintronic materials and devices will also be discussed.

Students should have taken “Introduction to Nanotechnology” and have an interest in
semiconductor materials and devices.

This module aims to give students a solid background in nanoelectronics and explore the operation of different devices.

At the end of the module students will
(i) Be able to explain the origin of electronic bands and bonding in materials
(ii) be able to show how electronic energy levels can be related to reduced dimensionality
(iii) be able to explain the current-voltage characteristics of tunnelling based devices
(iv) be able to explain the factors that govern current transport, include spin currents
(v) discuss the factors that control carbon nanotube based devices
(vi) discuss the operation of spintronic based devices.

Part A - Nanoelectronics in Low dimensional systems (Dr D Carey)

1. Revision of Electronic Materials: From atoms and orbitals to the bonding and structure of common metals, semiconductors and insulators. Simple band structure and reciprocal space description of important materials (Si, Ge, GaAs, carbon nanotubes and graphene). Relation to carrier mobility and conductivity. The Hall effect and carrier concentration.

2. Statistics in electron systems: Fermi-Dirac and Maxwell- Boltzmann Statistics; the nature of the Fermi level, degenerate and non-degenerate systems, Fermi energy and temperature, Density of states, calculation of occupancy and average energy.

3. Quantisation in low dimensional systems: From 3D to 0D: Calculation of density of states in lower dimensions, the confined energy level spectrum and sub-bands. Numerical solution to the finite quantum well problem. Calculating the carrier density with each sub-band.

4. Carrier Scattering Length scales, momentum and energy relaxation scales processes in particular phonon scattering and ionised impurity scattering mechanisms in selected systems.

5. 2D Materials and Devices: electron transport in 2D electron gas, mobility and scattering in 2D systems, modulation doping. High electron mobility transistors. Graphene nanoelectronics.

6. What limits current in a nanoscale device? Mesoscopic science, 1D systems, carrier injection, Landauer formulism, the nature of quantised conductance, ballistic and diffusive conduction mechanisms and scattering, relation to the mean free path. Calculating the transmission coefficient.

7. Quantum tunnelling devices: Double barrier structure and resonant tunnelling. Calculating the current density from the transmission coefficient in a resonant tunnel diode. Negative differential resistance based devices and figures of merit. Nature of Coulomb blockade. Flash memory devices.

8. Carbon nanotube and graphene based devices: including sensors and transistors. Vacuum nanoelectronics and noise in CNT based systems.


Part B - Spintronics - Materials and Devices (Prof. B Murdin)
1. The origin of electron spin and its implications, spin polarisation. Types of magnetism.
2. Spin current and spin valves
3. Giant and tunnel magnetoresistance, Spin Torque.
4. Spintronics materials and spin-FET.
5. Memories including magnetic RAM.

Lectures  - 30 hours in total

1. The Physics of Low-Dimensional Semiconductors, J Davies, ISBN 052148491X
2. Introduction to Nanoelectronics, V.V. Mitin, V.A. Kochelap and M.A. Stroscio, Cambridge University Press, ISBN 9780521881722. (2008)

3. Quantum Transport: Atom to Transistor, Supriyo Datta, Cambridge University Press, ISBN 0521631459 (2005)

4. Waser. R. (ed) Nanoelectronics and Information Technology: Advanced Electronic Materials and Novel Devices (Wiley-VCH, Weinheim, 2003)

5. Appropriate journal articles and review articles.

14th June 2010