Electrical characterization of thin films at the nanoscale
R.A. Gerhardt, S. Kumar
Georgia Institute of Technology, US
Keywords: impedance spectroscopy, dielectric spectroscopy, numerical simulation, film thickness, film conductivity
Abstract:Nanotechnology has opened up many interesting research avenues to investigate. With the new exciting developments in carbon nanotubes, graphene and synthesis of a wide range of nanomaterials and nanocomposites, the new challenges in terms of electrical property measurements have not yet been widely recognized. Often, measurements of these nano-objects and their devices are obtained by simply attaching contacts to them and reporting the measured values obtained. Little attention has been paid to whether the contacts are ohmic or not, or if the surrounding medium is contributing to the measured response or not. One technique that can potentially be used to help separate the different contributions is impedance spectroscopy. In this talk, we will first address some of these measurement challenges, by numerically calculating the impedance and dielectric response of films with thicknesses ranging from 10-100nm. The simulated spectra are shown to substantially depend not only on the film characteristics, but also on the properties of the supporting substrate as well as the size of the contacts and their configuration. Results indicate that these effects are more dramatic, the higher the conductivity of the film is. Supporting experimental evidence for some of the film configurations modeled will also be presented.