Graphene to Convert Electronic Signals in Gigahertz Range


Researchers pave the way for graphene-based nanoelectronics of the future

Scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) and the University of Duisburg-Essen (UDE), in cooperation with the Max Planck Institute for Polymer Research (MPI-P), have shown that graphene can convert electronic signals with frequencies in the gigahertz range.

Today’s silicon-based electronic components operate at clock rates of several hundred gigahertz (GHz), that is, they are switching several billion times per second. The electronics industry is currently trying to access the terahertz (THz) range, that is, up to thousand times faster clock rates.

Graphene can be an efficient nonlinear electronic material

Graphene has a high electrical conductivity and is compatible with all existing electronic technologies. It is predicted that graphene could be an efficient nonlinear electronic material. The researchers used graphene that contains many free electrons, which come from the interaction of graphene with the substrate onto which it is deposited, as well as with the ambient air.

If these mobile electrons are excited by an oscillating electric field, they share their energy quickly with the other electrons in graphene. This sharing of energy react much like a heated fluid which forms within the graphene. The change from the liquid to the vapour phase occurs within trillionths of a second and cause rapid and strong changes in the conductivity of graphene. This is the key effect which leads to the frequency multiplication.

The researchers used electromagnetic pulses from the TELBE facility with frequencies between 300 gigahertz to 680 gigahertz. They converted them in graphene into electromagnetic pulses with three, five and seven times of the initial frequency, that is, up-converted them into the terahertz frequency range.

Measured values to predict the properties of nanoelectronics

The agreement of measured values with thermodynamic model suggests that they will also be able to use it to predict the properties of nanoelectronic devices made of graphene.
They also demonstrated that carbon-based electronics can operate efficiently at ultrafast rates. Ultrafast hybrid components made of graphene and traditional semiconductors are also conceivable.

Well, the experiment was performed using the superconducting-accelerator-based TELBE terahertz radiation source at the ELBE Center for High-Power Radiation Sources at the HZDR. Its hundred times higher pulse rate compared to typical laser-based terahertz sources made the measurement accuracy required for the investigation of graphene.

A data processing method developed as part of the EU project EUCALL allows the researchers to use the measurement data taken with each of the 100,000 light pulses per second. In terms of measurement technology, they are at the limit of what is currently feasible.