Intermixing of motional currents in suspended CNT-FET based resonators

Abstract

Here, we report the intermixing of piezoresistive and conduction modulation current in a carbon nanotube field effect transistor (CNT-FET) based resonator. We show that due to static displacement of the nanotube, as a result of electrostatic actuation, the motional current at the resonance frequency consist of both current components. For instance at a DC gate bias of 1.3 V, 3/4 of the motional current is conduction modulation current while the rest arises from piezoresistive effects. The intermixing effect due to asymmetry influences the fundamental harmonic response as well as the physical nature of the electrical signal being sensed; both of which are important for understanding frequency harmonics in nanoresonators and developing efficient readout schemes for nanoscale sensors.

A Phase-Consistent Model for the Spectral Transfer Function of Carbon Nanotube Resonators

“…Previous models in literature [3][4] introduce the adhoc phase in the background current and assume a Lorentzian spectral function for a pure transconductive motional current. More recent studies also included the piezoresistive current, but the phase was widely neglected [5]. Here, we propose a new model incorporating both transconductive and piezoresistive current contributions based on harmonic balancing (HB) removing the linear regime assumption implicit in the Lorentzian peak shape.…”