Effect of Top Dielectric Medium on Gate Capacitance of Graphene Field Effect Transistors: Implications in Mobility Measurements and Sensor Applications

• Published in: Nano letters 2010-12, Vol.10 (12), p.5060-5064
• Main Authors: Xia, J. L, Chen, F, Wiktor, P, Ferry, D. K, Tao, N. J
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Electronics; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Specific materials; Transistors
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl103306a

We have carried out Hall measurement on back-gated graphene field effect transistors (FET) with and without a top dielectric medium. The gate efficiency increases by up to 2 orders of magnitude in the presence of a high κ top dielectric medium, but the mobility does not change significantly. Our measurement further shows that the back-gate capacitance is enhanced dramatically by the top dielectric medium, and the enhancement increases with the size of the top dielectric medium. Our work strongly suggests that the previously reported top dielectric medium-induced charge transport properties of graphene FETs are possibly due to the increase of gate capacitance, rather than enhancement of carrier mobility.