A seamless-pitched graphene nanoribbon field effect transistor

Abstract

This paper proposes a graphene nanoribbon field effect transistor (GNRFET) consisting of pitched semiconducting GNRs as the channels that are connected to the metallic graphene source/drain in a seamless fashion. We obtained the diagrams for frequency bandwidths, step time responses, and Nyquist stability for the seamless pitched GNRFET (SP-GNRFET) with a channel having 100 pitched GNRs at 10nm pitch in the common source configuration with various dimensions of the GNRs. The aforementioned diagrams were also obtained for the pitched carbon nanotube field effect transistor (CNTFET) with a channel having 100 pitched CNTs at 10nm pitch in the common source configuration with various dimensions of the CNTs. In order to compare the SP-GNRFET and the pitched CNTFET, physical parameters of the GNRs/CNTs were assumed to be the same in both devices. The results show that when the dimensions of GNRs in the SP-GNRFET increase, the frequency bandwidth decreases, but relaxation time and Nyquist stability increase. Moreover, with an increase in the dimensions of CNTs, similar behavior is observed for the pitched CNTFET.The results also show that the frequency bandwidth of SP-GNRFET is in the range of 10THz and is more than that of the pitched CNTFET by two orders of magnitude. This is achieved by eliminating the Schottky barrier between the channels and source/drain contacts in the SP-GNRFET. Nevertheless, step time responses for the SP-GNRFET show multi-harmonic oscillations like those for the pitched CNTFET. This shows the importance of stability analysis as a challenge to the SP-GNRFET. Nyquist diagrams predict lower stability for SP-GNRFETs than for pitched CNTFETs. This is because elimination of the Schottky barrier results in a reduction in the overall impedance of the SP-GNRFET, which in turn leads to the frequency of the fluctuations in the SP-GNRFET being more than that in the pitched CNTFET.