Jan 22, 2013
Reduced graphene oxide passes high-frequency transmission test
Nanoelectronics experts at Yonsei University in Korea have been studying high-frequency transmission in reduced graphene oxide (rGO) sheets at radio frequencies. The material is attracting considerable interest in fields such as electronics and chemistry thanks to its solubility in water and high functionality. Easy and simple production routes make rGO very attractive to developers, but the limit on electrical conductivity due to lattice defects has seemed hard to avoid, at least for DC transmission. High-frequency signal transmission on the other hand can present a different picture.
In recent work, the team analysed the high-frequency transmission characteristics of the system through S-parameter measurements, which revealed that such limitations in DC transmission can be minimized in the high frequency range. Samples of rGO of various thicknesses were composed by dielectrophoresis and, in testing, sheets measuring only a few nanometres in thickness showed very stable and competitive high-frequency transmission capability.
The impedance of the rGO sheets decreased consistently over the entire frequency range. Also, the equivalent circuit model to separate the impedance into passive electrical properties provided further analytical results. For example, the intrinsic capacitance suggested further capacitive coupling along the device, which led to low electrical conductivity at the high-frequency range. In addition, among the various passive electrical parameters, the contact resistance between the metal electrodes and the rGO sheet was considered as the most serious limitation in the transmission of high-frequency signals while the intrinsic resistance was decreased drastically.
Given the material’s advantages in terms of its fabrication process and biochemical functionality, the results suggest that potential applications for rGO sheets could include RF sensors and high-frequency interconnects.
Additional details can be found in the journal Nanotechnology.
About the author
Hyung Seo Yoon is a PhD candidate in the Department of Mechanical Engineering at Yonsei University, Korea, under the supervision of Seong Chan Jun, associate professor of Yonsei University. His research team has strong interests in nanomaterial science and nanoelectronic devices.