Department of Physics

Staff profile

Dr Stuart Brand, B.Sc. Physics, Ph.D. (Theoretical Studies of Localized Defects in Semiconductors)

Personal web page

Senior Lecturer in the Department of Physics
Telephone: +44 (0) 191 33 43537
Room number: 147

(email at stuart.brand@durham.ac.uk)

Biography

  I) Responsibilities within department

L3 Semiconductors and Dielectrics lecture courses, Python Computing labs. demonstating, General Problems Class demonstrating, L4 Course Director.

Research Interests

  I) Semiconductors

Traditionally, my interests have been centred mainly on bandstructure-related theoretical calculations. I began in the field of localized defects in semiconductors, considering, in particular, vacancies and vacancy-impurity complex defects. I have also worked on Auger and impact ionization processes in semiconductors employing realistic empirical pseudopotential bandstructure models to perform rate calculations. Low dimensional structures - quantum wells and superlattices - have also been a topic of interest .

I have also been involved with the development of and use of first principles calculations to study the properties of nitride materials such as GaN, In and AlN and their surface morphology/reconstructions .  

Currently, however, I am principally concerned with the theoretical and experimental study of

  II) Photonic Band Gap (PBG) Systems

Structures consisting of a periodically varying (in 1-, 2- or 3-D) refractive index exhibit properties analogous to those of electronic systems and the same type of conventional or complex  band-structure plane-wave calculation approach can be employed to model such photonic systems.  A variety of disordered, periodic and aperiodic (e.g. 1-D Fibonacci and 2-D Penrose tile)  or  quasi-crystal systems have been studied, some in collaboration with experimental groups. Part of this work has focused on the study of negative refraction effects and the design of filters in the terahertz frequency regime in collaboration with experimental colleagues in both the Physics and Engineering departments at Durham. 

As they are much easier to fabricate, much of the work has concentrated on structures involving 1-D Bragg stacks. These can be employed to study the detailed properties of a specialised type of localized photonic state called a Tamm plasmon polariton which exists at the interface between the Bragg stack and a metallic layer. Such states have the potential to be useful in a new generation of optoelectronic devices.  An interesting structure which is a subject of current experimental study consists of a pair of prisms with Bragg stacks deposited on their hypotenuse separated by a small air gap. Light incident on this system above the critical angle would normally be totally internally reflected - indeed the existence of a photonic band gap acts as an additional barrier to transmission through the system. However, due to the presence of photonic interface states, which can interact to form S(ymmetric) and A(ntisymmetric) combinations, this system, which involves only a single cavity (the air gap), behaves in an analogous fashion to that of a more conventional dual cavity structure. By altering the size of the gap the resulting transmitted and reflected radiation can, in principle, be tuned to produce narrow band or notch filters or a narrow transmission line pair with a separation in the terahertz regime. The enhanced fields near the interfaces may also be of interest for a variety of applications. 

Research Groups

Selected Publications

Journal papers: academic

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Supervises