Lyman L. Handy Colloquium Series
Semiconductor Nanomembranes: Sheet Science and Technology
Professor Max G. Lagally
University of Wisconsin-Madison
Semiconductor nanomembranes, extremely thin single-crystal sheets, are distinguished from traditional epitaxial films in that in some part of their life they are completely free of substrate constraints. Their properties (mechanical, electronic, photonic, phononic,...) differ significantly from those of bulk semiconductor counterparts. The primary drivers in these differences, 1) the large surface-to-volume ratio, 2) the extremely low flexural stiffness relative to that of the bulk, and 3) the ability to accept high values of strain, provide a significant potential for a disruptive nanotechnology platform, with new or enhanced application in fast flexible and quantum electronics; new nanophotonic, optoelectronic, and thermoelectric devices; chemical and biological sensors, microfluidics and biology, and opto- and electromechanical nanosystems.
Nanomembranes can take on a large range of shapes (tubes, spirals, ribbons, wires) via appropriate strain engineering and patterning. The ability to introduce strain into thin semiconductor sheets allows not only the modification of shape and of band structure both globally and locally, but also allows the creation of materials with properties not achievable with conventional approaches. Because they are flexible, nanomembranes are readily transferable to other hosts and conform and bond easily, and in large part adopt the mechanical properties of the host. The consequent ability also to stack membranes allows the integration of different materials and/or orientations.
This talk addresses the above properties using examples from Group IV semiconductors. New or unexpected physical and electronic properties will be highlighted, with emphasis on effects associated with ultra-flexibility and with strain engineering.
Time and Location
Thursday, March 8, 2012
Seminar at 12:45 p.m.
ZHS Room 159
The scientific community is cordially invited.