11-06/07 :: June/July 2011

nanotimes Research

13

Writing Nanostructures // Heated AFM Tip Allows Plastic and CMOS-Compatible Direct Fabrication of Ferroelectric Piezoelectric Structures © Text: Gatech / John Toon

R

esearchers at Georgia Institute of Technology, University of Nebraska-Lincoln, and University

of Illinois Urbana-Champaign, USA, have deve- loped a new way to fabricate nanometer-scale ferroelectric structures directly on flexible plastic substrates that would be unable to withstand the processing temperatures normally required to create such nanostructures.

The technique, which uses a heated atomic force microscope (AFM) tip to produce patterns, could fa- cilitate high-density, low-cost production of complex ferroelectric structures for energy harvesting arrays, sensors and actuators in nano-electromechanical systems (NEMS) and micro-electromechanical sy- stems (MEMS).

“We can directly create piezoelectric materials of the shape we want, where we want them, on flexible substrates for use in energy harvesting and other ap- plications,” said Nazanin Bassiri-Gharb, co-author of the paper and an assistant professor in the School of Mechanical Engineering at the Georgia Institute of Technology. “This is the first time that structures like these have been directly grown with a CMOS- compatible process at such a small resolution. Not only have we been able to grow these ferroelectric

SEM-image shows a large PZT line array crystallized on a 240-nanometer thick precursor film on a platinized silicon wafer.

© Yaser Bastani/Gatech

structures at low substrate temperatures, but we have also been able to pattern them at very small scales.”

The researchers have produced wires approximately 30 nanometers wide and spheres with diameters of approximately 10 nanometers using the patterning technique. Spheres with potential application as ferroelectric memory were fabricated at densities exceeding 200 gigabytes per square inch – currently the record for this perovskite-type ferroelectric ma-