Microdielectric Measurements of Pristine and Modified thin Fullerene (C60) Films

ABSTRACTAs developed by Senturia and co-workers [1], microdielectrometry is a technique for measuring complex permittivity utilizing microfabrication technology to incorporate both the interdigital sensing electrodes and associated circuitry on the same microchip. By covering a microdielectrometer chip with a thin layer of C60, it is possible to dynamically monitor the film's frequency response and dielectric properties as a function of doping with selected gases and other species.It is known that solid C60 has a substantial amount of interstitial volume. The presence of mobile ions in these spaces compromises the breakdown voltage and makes pure C60 unsuitable for applications requiring high-quality dielectric films. However, various immobile ions or neutral species (e.g. oxygen) can be made to fill the interstitial volume, changing the characteristics of the C60 films and, in some cases, improving the dielectric properties. In-situ microdielectric measurements of pristine and modified C60 films were performed for frequencies ranging from 0.005 Hz to 100 kHz. Based on the low-frequency behavior of the dielectric constant, a model is proposed for the mechanism of oxygen diffusion into the interstitial spaces of the fullerene material.