World’s fastest graphene transistor unveiled by IBM

The high frequency record was achieved using a wafer scale, epitaxially grown graphene using processing technology compatible to that used in advanced silicon device fabrication. The accomplishment, published in Science is a key milestone for the Carbon Electronics for RF Applications (CERA) programme funded by DARPA, in an effort to develop next generation communication devices. Uniform and high quality graphene wafers were synthesised by thermal decomposition of a silicon carbide (SiC) substrate. The graphene transistor itself utilised a metal top gate architecture and a novel gate insulator stack involving a polymer and a high dielectric constant oxide. The gate length was 240nm, leaving plenty of space for further optimisation of its performance by scaling down the gate length. According to IBM, 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 (~ 40GHz). Similar performance was obtained from devices based on graphene obtained from natural graphite, proving that high performance can be obtained from graphene of different origins. Previously, the team had demonstrated graphene transistors with a cut off frequency of 26GHz using graphene flakes extracted from natural graphite. Dr Tze-Chiang Chen, pictured, vice president, Science and Technology, IBM Research, said: "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. The breakthrough we are announcing demonstrates clearly that graphene can be utilised to produce high performance devices and integrated circuits."