Silicon nanomembranes are suspended sheets of single-crystal silicon, less than a few hundred nanometers thick, with areas exceeding thousands of square micrometers. Challenges in fabrication arise from strains in the silicon-on-insulator (SOI) starting material, which result in buckling instabilities in thin membranes. I recently developed a simple technique to fabricate flat nanomembranes, with thicknesses as low as 5 nm, using an elastically metastable configuration that is subsequently stabilized. The technique involves embracing, rather than avoiding, the effects of stiction, which are typically considered a detriment to MEMS fabrication. This ability to easily produce flat nanomembranes beyond the buckling threshold expands opportunities to study nanoscale properties free from the influence of a nearby substrate, but also provides a technology platform for smaller and more sensitive MEMS devices, from high-sensitivity, low-footprint pressure sensors to lab-on-a-chip devices for macromolecular separation and sensing.
Dr. Gokul Gopalakrishnan is a B. Tech graduate from IIT - Madras, in Metallurgical Engineering. His doctoral work in the Physics Department at the Ohio State University involved studying phonon mediated quantum Hall phenomena in two-dimensional electron gases. He went on to a postdoctoral fellowship at Harvard University, where he investigated the metal-insulator transition in thin film and nanostructured vanadium dioxide, a technologically interesting material for high-speed optoelectronic devices. As a research associate at the University of Wisconsin - Madison, Dr. Gopalakrishnan developed x-ray scattering tools to probe phonons in nanoscale crystalline solids. Currently with the Engineering Physics Department at the University of Wisconsin - Platteville, he is developing techniques to fabricate and characterize freestanding semiconductor nanostructures and related device elements that are important for the science and technology of micro- and nano-electromechanical systems. He is also a board member for the Regional Materials and Manufacturing Network, an academic-industry consortium to streamline materials research and development.