Improving the performance of graphene nanoribbon field-effect transistors by using lanthanum aluminate as the gate dielectric

Abstract

In nanoscale transistors, electron tunneling increases and causes a large leakage current due to the reduced channel length and gate oxide thickness. To reduce the short-channel effects and leakage current, the gate oxide can be selected from materials with high dielectric constant. In this paper, lanthanum aluminate (LaAlO3), a material with a high dielectric coefficient, is used as a gate dielectric in the structure of graphene nanoribbon field-effect transistors (GNRFET) and the effect of using this material on the device performance is studied. The transistor characteristics are extracted from device simulations performed by self-consistently solving the Poisson and Schrodinger equations in the nonequilibrium Green’s function formalism, employing the tight-binding approximation in the mode-space and ballistic regime. The ON-state and OFF-state currents, the ION/IOFF ratio, the threshold voltage, the drain-induced barrier lowering (DIBL), the subthreshold swing, and the transconductance (gm) are calculated for LaAlO3 as well as different materials as the gate dielectric to investigate the device performance. Based on the simulation results, the use of LaAlO3 as the gate dielectric in the transistor structure instead of other materials leads to larger values of the ON-state current, ION/IOFF ratio, and gm as well as smaller values of the OFF-state current, threshold voltage, DIBL, and subthreshold swing. According to the obtained results and excellent properties of LaAlO3, the use of this material could improve the performance of GNRFETs.