Black Phosphorus NEMS Resonant Infrared (IR) Detector

We report on the first experimental demonstration of two-dimensional (2D) black phosphorus (P) resonant nano-electromechanical systems (NEMS) for infrared (IR) detection, enabled by black P vibrating channel transistors (VCTs). Resonant motions of the black P NEMS are excited and read out all-electrically, thanks to black P crystal's high field-effect mobility and highly efficient channel conductance modulation via resonant motion. Given the narrow direct bandgap ($E_{\mathrm{g}}\approx 0.3\text{eV}$) intrinsically suited for infrared (IR) detection, the black P crystalline NEMS resonators are highly responsive, and readily detect IR radiation by utilizing resonance frequency shift upon absorption of incident IR. The measurements achieve excellent IR responsivity, $\Re=-0.31\ \text{kHz}/\mu\mathrm{W}$, from a 2D black P drumhead NEMS resonator, at 785nm near infrared (NIR) wavelength. Toward enabling real-time IR sensing, we further demonstrate sensitive all-electrical transduction of resonances of 2D black P NEMS, in direct two-port transmission measurement of VCTs, by employing a local gate, thus evading the need of any conventional frequency down-mixing or conversion techniques.