John Stewart Preston
Professor, Engineering Physics

The overarching theme of my research group is the application of lasers in the creation, fabrication and analysis of novel materials that are of interest for future devices. A major focus of our current work is the need for better materials and processes for solar cells.

Pulsed Laser Deposition
We operate three chambers for laser ablative deposition of thin films: one optimized for very pure materials, one for large area deposition and most recently a new UHV chamber for oxygen sensitive materials. One aspect of developing novel systems is that extensive characterization studies are always required. We make extensive use of the world-class facilities available in the Brockhouse Materials Research Institute including the Canadian Centre for Electron Microscopy (http://ccem.mcmaster.ca/) and the McMaster Analytical X-Ray Facility (MAX).

Self-Assembly of Epitaxial Nanostructures
An area of particular interest to my group is the exploration of the epitaxial arrangements that are possible for dissimilar material systems. Recent work has looked at gold on spinel crystals and CdTe nanostructures on sapphire. Nanoscale pillars, wires, pyramids and globes can self-assemble driven by strain and surface tension.

Photovoltaics
We have current projects looking at novel enhancements to silicon solar cells, new types of II-VI solar cells and hybrid cells using nanostructures and organic materials. We are also developing entirely new material systems that offer at least the potential of exceptional photovoltaic performance. I am also the Director of the NSERC CREATE Program in Photovoltaics.