Self-Transducing Silicon Nanowire Electromechanical Systems at Room Temperature

Abstract

Electronic readout of the motions of genuinely nanoscale mechanical devices at room temperature imposes an important challenge for the integration and application of nanoelectromechanical systems (NEMS). Here, we report the first experiments on piezoresistively transduced very high frequency Si nanowire (SiNW) resonators with on-chip electronic actuation at room temperature. We have demonstrated that, for very thin (∼90 nm down to ∼30 nm) SiNWs, their time-varying strain can be exploited for self-transducing the devices' resonant motions at frequencies as high as ∼100 MHz. The strain of wire elongation, which is only second-order in doubly clamped structures, enables efficient displacement transducer because of the enhanced piezoresistance effect in these SiNWs. This intrinsically integrated transducer is uniquely suited for a class of very thin wires and beams where metallization and multilayer complex patterning on devices become impractical. The 30 nm thin SiNW NEMS offer exceptional mass sensitivities in the subzeptogram range. This demonstration makes it promising to advance toward NEMS sensors based on ultrathin and even molecular-scale SiNWs, and their monolithic integration with microelectronics on the same chip.

High-sensitivity linear piezoresistive transduction for nanomechanical beam resonators

“…Also, we have performed a theoretical estimation of the vibration amplitude by modelling the capacitance between the NWs and the actuation electrode. Our estimations provide values of the order of 1 nm, which is consistent with previously reported estimations for similar devices electrostatically driven in similar conditions 2,3 . Although these qualitative considerations only set an upper limit for the amplitude of around 10 nm and a typical order of magnitude of around 1 nm, they show that the vibration amplitude a n is typically much smaller than the maximum deflection at rest d 0 .…”

“…Remarkably, the resonance peaks of Fig. 2c,d produce larger (cleaner) signals than those reported previously for SiNW resonators 2,3,19 . Besides the fundamental modes, we find it possible to detect higher-order modes, even at frequencies higher than 500 MHz, for which the vibration amplitude is expected to be very small.…”

“…1) and two-source/2o (ref. 2). Details about the experimental implementation of each detection scheme can be found in Methods.…”

“…D oubly clamped beams based on nanostructures such as carbon nanotubes (CNTs) 1 and silicon nanowires (SiNWs) 2,3 are excellent building blocks for the realization of nanomechanical resonators with ultra-highperformance characteristics. Such devices have provided functional features at the verge of fundamental limits in several contexts, ranging from physical sensing [4][5][6] to signal processing 7,8 .…”

Regularization of chaos by noise in electrically driven nanowire systems

“…To see why NEM systems are fundamentally nonlinear and thus chaos can arise, we take as an example an electrostatically driven nanowire [1,2,8,9,[12][13][14][20][21][22], a paradigm for investigating nonlinear behaviors in nanoscale systems [15,18,19]. When the nanowire moves, the amount of stretching can be expressed as an integral of nonlinear functions of the displacements (see Sec.…”