Simple thermodynamics defines the performance of ultrafast
graphene transistors and photodetectors
(July 16, 2015) Mainz/Barcelona.
A team of scientists at the Max Planck Institute for Polymer Research (MPI-P)
discovered that electrical conduction in graphene on the picosecond timescale –
a picosecond being one thousandth of one billionth of a second – is governed by
the same basic laws that describe the thermal properties of gases. This much
simpler thermodynamic approach to the electrical conduction in graphene will
allow scientists and engineers not only to better understand but also to
improve the performance of graphene-based nanoelectronic devices.
The researchers found that the energy of ultrafast electrical
currents passing through graphene is very efficiently converted into electron
heat, making graphene electrons behave just like a hot gas. “The heat is
distributed evenly over all electrons. And the rise in electronic temperature,
caused by the passing currents, in turn has a strong effect on the electrical
conduction of graphene” explains Professor Mischa Bonn, Director at the MPI-P.
The study, entitled “Thermodynamic picture of ultrafast charge transport in
graphene”, has recently been published in Nature Communications.
Graphene – a single sheet of carbon atoms – is known to be a
very good electrical conductor. As a result, graphene finds a multitude of
applications in modern nanoelectronics. They range from highly efficient
detectors for optical and wireless communications to transistors operating at
very high speeds. A constantly increasing demand for telecommunication
bandwidth requires an ever faster operation of electronic devices, pushing
their response times to be as short as a picosecond. “The results of this study
will help improve the performance of graphene-based nanoelectronic devices such
as ultra-high speed transistors and photodetectors” says Professor Dmitry
Turchinovich, who led the research at the MPI-P. In particular they show the
way for breaking the terahertz operation speed barrier – i.e. one thousand
billions of oscillations per second – for graphene transistors.