Position: Ph.D. Candidate

Current Institution: MIT

Abstract:
Probing and Tuning the Nanoscale Enabling Active Nanodevices

At the nanoscale, unique properties and phenomena emerge leading to scientific and technological paradigms beyond those classically envisioned. My research implements an interdisciplinary approach to precisely probe and tune the nanoscale, study the emerging physical principles and utilize those to develop devices with new and improved functionalities. A particular focus of my work is controlled and reversible tuning of nanostructured configurations to achieve dynamic modulation of electrical and optical properties. Such tunability provides mechanisms that make feasible active nanodevices with broad applications.

Studying the nanoscale necessitates precise development of features few nanometers in dimensions. Conventional fabrication techniques often lack the desired resolution and introduce imperfections interfering with the device function. My research addresses these challenges by developing alternative fabrication techniques in which control of surfaces and interfaces directs the assembly of nanostructured components into larger functional units with nanometer precision. To achieve tunability in these structures an approach I have implemented involves utilizing mechanically conformal components such as organic molecules in the design. In this scheme, conformational changes of the active component through an applied external stimulus result in controlled and reversible tunability of the device architecture and subsequently its performance.

Utilizing these principles, I have demonstrated a tunneling electromechanical switch composed of a sub-5 nm metal-molecule-metal switching gap. In this design, electrostatically-induced mechanical compression of the molecular layer modulates the distance between the electrodes, leading to an exponential increase in the tunneling current that defines an abrupt switching. The molecular layer helps form switching gaps only few nanometers thick, dimensions much smaller than conventionally feasible, thus enabling operating voltages much lower than that of the conventional nanoelectromechanical switches. During the switching operation, the elastic force in the compressed molecular layer can overcome the surface adhesive forces between the approaching electrodes. This force control prevents the permanent adhesion of these components, referred to as stiction, overcoming a common failure mode of electromechanical systems. With low operating voltages and repeatable performance, these switches have promising applications in energy efficient electronics. Conformational changes can also alter the interaction of light with nanostructures. My research has exploited this property to develop dynamically tunable plasmonic structures in which nanometer changes in device conformation result in modulation of the plasmon resonance. These active plasmonics provide a platform for various applications including nanoscale metrology techniques and on-chip optical sources.

Bio:
Farnaz Niroui is a Ph.D. candidate in the Department of Electrical Engineering and Computer Science at Massachusetts Institute of Technology where she works with Professors Vladimir Bulovic and Jeffrey Lang. Her research interest is at the interface of device physics, nanofabrication, and materials science to study, manipulate and engineer devices and systems with unique functionalities at the nanoscale. Farnaz is a recipient of the Natural Sciences and Engineering Research Council of Canada Scholarship for graduate studies. She received her Master of Science degree in Electrical Engineering from MIT in 2013 and completed her undergraduate studies in Nanotechnology Engineering at University of Waterloo in 2011.