Kristine I. Spangard, Department Coordinator
One of the most pressing technological challenges facing the world today is the need for inexpensive carbon-free energy. Electricity generation by solar cells (photovoltaics) is a potential solution to this problem. The most common type of solar cell is made from materials called semiconductors, and the most common semiconductor used is silicon. However, while exhibiting good performance, conventional silicon-based solar cells are expensive to produce. Thus there is interest in other approaches to solar cell fabrication which should result in less expensive production costs without too great a sacrifice in conversion efficiency. One of these approaches uses thin films of strongly absorbing semiconductors deposited on inexpensive substrates such as glass and metal films.
The goal of photovoltaics research at Macalester is to understand and optimize alternative methods for producing thin film semiconductors that can be used in commercial solar cells. Work currently underway includes reactive magnetron sputtering for the deposition of hydrogenated amorphous silicon-germanium thin films to be used as solar cell absorber layers, reactive magnetron sputtering for the deposition of conductive zinc oxide thin films to be used as solar cell window layers, electrodeposition of copper indium disulfide thin films for solar cell absorber layers, and simulation and modeling of hot-wire deposition of thin film silicon absorber layers. Like most applied science, the work is very multidisciplinary, drawing on materials physics, condensed matter physics, plasma physics, chemistry, and transport theory.