Metal-Insulator-Semiconductor Junctions for Efficient and Stable Solar Fuel Synthesis
Paul C. McIntyre, Sc.D.
Department of Materials Science and Engineering, Stanford University
ABSTRACT
Energy storage to overcome the intermittency of solar radiation is a major challenge for adoption of solar energy at very large scale. Photoelectrochemical synthesis of fuels from sunlight is one potential storage approach. Using sunlight to drive photoelectrochemical reactions requires electronically coupling light absorbing materials and catalysts to simultaneously achieve a) efficient absorption of sunlight, b) efficient electron-hole separation and transport, and c) surfaces with high electrochemical reactivity, all while avoiding corrosion or oxidation that would destroy one or more of the above properties. We have recently shown that atomic layer deposition (ALD) can be used to protect the surface of silicon so that it can serve as a stable photoanode for water splitting. Water oxidation, which has long been recognized as a key step in fuel synthesis from sunlight, is a photoelectrochemical reaction that would normally cause Si and many other high-quality absorbers to oxidize destructively.
This presentation will focus on our recent work in which ultrathin ALD-grown TiO2 provides a protective metal oxide passivation that stabilizes the heretofore unstable silicon surface under water oxidation conditions while also permitting facile hole transport to an overlying water oxidation catalyst. Mechanisms of electronic conduction in these nanoscale MIS junctions will be summarized, and the potential for extending ALD surface protection to other interesting absorbers beyond silicon will be discussed.
BIOSKETCH
Paul McIntyre is Professor of Materials Science and Engineering, Senior Fellow of the Precourt Institute for Energy, and Director of the Geballe Laboratory for Advanced Materials at Stanford University. He is also Faculty Co-Director of Stanford’s Energy and Environment Affiliates program. McIntyre leads a research team of approximately fifteen graduate students, post-doctoral researchers, visiting scientists and consulting professors who perform basic research on nanostructured inorganic materials for applications in electronics and energy technologies. He is best known for his work on metal oxide/semiconductor interfaces, ultrathin metal oxide films, atomic layer deposition, and semiconductor nanowires. His research team synthesizes materials, characterizes their structures and compositions with a variety of advanced microscopies and spectroscopies, studies the passivation of their interfaces, and measures functional properties of devices. Their research is supported by several U.S. government agencies and major semiconductor manufacturers world-wide. McIntyre is an author of approximately 170 archival journal papers and inventor of 8 US patents, and has given over 100 invited presentations, plenary talks and tutorial lectures. He has received two IBM Faculty Awards, a Charles Lee Powell Foundation Faculty Scholarship and an SRC Inventor Recognition award. McIntyre was a GCEP Distinguished Lecturer in 2010 and received the Woody White Award of the Materials Research Society in 2011.