In sufficiently small objects the laws of physics are very different to those in the everyday macroscopic objects we are used to.
At the nanoscale, the laws of quantum (rather than classical) physics become important and provide opportunities for many new and exciting fundamental discoveries, as well as building new materials and new novel electronic devices.
This work forms part of the programme of the in the MacDiarmid Institute for Advanced Materials and Nanotechnology.
Prof Simon Brown - research interests
The research in my group is focused on two main objectives:
We use atomic clusters as building blocks for the formation of nano-electronic devices, and explore the novel properties of those devices. Over the past few years we have developed cluster-based devices with applications ranging from chemical sensors to magnetic field sensors to transistors.
We are currently focusing on understanding novel switching behavior in these devices, similar to the behaviour of memristors. We have found that atomic scale wires are formed in tunnel gaps within a percolating film, leading to quantised conductances and cascades of switching events that resemble the learning processes in the human brain. Because the structures are similar to those in the brain, these ‘neuromorphic devices’ show promise for computational tasks (like image processing) that the brain is good at, but which even modern supercomputers find difficult.
We have shown that we can grow many interesting types of nanostructures by simply depositing atoms on to very smooth surfaces and letting them self-assemble. We have focused on growing nanostructures of bismuth and related materials on graphite, and have, for example, shown that they exhibit quantum size effects, where the sizes of the structures are determined by the electronic states inside them. In a new project we are building on this previous work to investigate topological nanostructures grown by similar methods. ‘Topological Insulators’ are one of the hottest topics in physics right now, but very little work has been done on nanostructures.
- The structure of atomic clusters.
- Optical studies of Reactive Ion Etched GaN
- Optical studies of amorphous GaN and GaN / AlN superlattices
- Optical studies of many body effects in semiconductor quantum wells.
- Resonant tunneling in high magnetic fields.
- Molecular dynamics simulations of cluster structure