Physics Today: IBM researchers demonstrated a radio-frequency graphene transistor with the highest cut-off frequency achieved so far for any graphene device—100 billion cycles/second (100 gigahertz).
The high frequency record was achieved using wafer-scale, epitaxially grown graphene using processing technology compatible to that used in advanced silicon device fabrication.
"A key advantage of graphene lies in the very high speeds in which electrons propagate, which is essential for achieving high-speed, high-performance next generation transistors," said T. C. Chen, vice president of science and technology, IBM Research. "The breakthrough we are announcing demonstrates clearly that graphene can be utilized to produce high performance devices and integrated circuits."
Graphene is a single atom-thick layer of carbon atoms bonded in a hexagonal honeycomb-like arrangement. This two-dimensional form of carbon has unique electrical, optical, mechanical, and thermal properties, and its technological applications are being explored intensely.
Uniform and high-quality graphene wafers were synthesized by thermal decomposition of a silicon carbide (SiC) substrate. The graphene transistor itself utilized a metal top-gate architecture and a novel gate insulator stack involving a polymer and a high dielectric constant oxide. The gate length was modest, 240 nanometers, leaving plenty of space for further optimization of its performance by scaling down the gate length.
The frequency performance of the graphene device already exceeds the cut-off frequency of state-of-the-art silicon transistors of the same gate length (~ 40 GHz).
100 GigaHertz. Sounds almost freaky.
If and when they are able to varify 1 TeraHertz chips, a compact source for producing T-waves might avail itself.
I have often wondered about 100 TeraHertz or even 1 PetaHertz chips as far as any novel electromagnetic wave fronts that would result in the associated visible or near visible light frequencies.
Now I am not talking the typical mode of visible light, UV A,B,& C, and near visible IR, generation such as by atomic collisions, changes in electronic configurations of individual atoms and molecules, nor as a result of individual photon-atom or photon molecule scattering, but rather am contemplating a whole sale current change of macroscopic scale such as within a transistor involving classical-electro-dynamic scale electromotive force, to use an old fashioned term.
I do not know what to expect that would be different from ordinary 100 TeraHertz EM radiation generated by conventional artificial and conventional natural means, but perhaps the electromagnetic field topologies of such transistor generated ~ visible light waves, or photons if you will, might have some cool applications.
Work like the development of the 100 Gigahertz graphene chip is classical electrodynamics at its finest.