Black Phosphorus Nanoelectromechanical Resonators Vibrating at Very High Frequencies

TL;DR

This paper demonstrates black phosphorus nanoelectromechanical resonators vibrating at very high frequencies, highlighting their potential for high-speed devices and coupling with electronic properties.

Contribution

It introduces a new black phosphorus resonator fabrication method and explores their high-frequency vibrational responses using electrical and optical excitation.

Findings

Resonators reach frequencies up to ~100MHz.

Black phosphorus flakes exhibit elastic behavior from plate to membrane regimes.

Thin flakes show promise for high-speed vibratory and electronic applications.

Abstract

We report on experimental demonstration of a new type of nanoelectromechanical resonators based on black phosphorus crystals. Facilitated by a highly efficient dry transfer technique, crystalline black phosphorus flakes are harnessed to enable drumhead resonators vibrating at high and very high frequencies (HF and VHF bands, up to ~100MHz). We investigate the resonant vibrational responses from the black phosphorus crystals by devising both electrical and optical excitation schemes, in addition to measuring the undriven thermomechanical motions in these suspended nanostructures. Flakes with thicknesses from ~200nm down to ~20nm clearly exhibit elastic characteristics transitioning from the plate to the membrane regime. Both frequency- and time-domain measurements of the nanomechanical resonances show that very thin black phosphorus crystals hold interesting promises for moveable and vibratory devices, and for semiconductor transducers where high-speed mechanical motions could be coupled to the attractive electronic and optoelectronic properties of black phosphorus.