Nanomechanical Spectroscopy of 2D Materials
Jan Kirchhof, Yuefeng Yu, Gabriel Antheaume, Georgy Gordeev, Denis Yagodkin, Peter Elliott, Daniel B. de Araújo, S. Sharma, Stephanie Reich, Kirill I. Bolotin
Abstract
We introduce a nanomechanical platform for fast and sensitive measurements of the spectrally resolved optical dielectric function of 2D materials. At the heart of our approach is a suspended 2D material integrated into a high Q silicon nitride nanomechanical resonator illuminated by a wavelength-tunable laser source. From the heating-related frequency shift of the resonator as well as its optical reflection measured as a function of photon energy, we obtain the real and imaginary parts of the dielectric function. Our measurements are unaffected by substrate-related screening and do not require any assumptions on the underling optical constants. This fast (τrise ∼ 135 ns), sensitive (noise-equivalent power = 90pW√Hz), and broadband (1.2–3.1 eV, extendable to UV–THz) method provides an attractive alternative to spectroscopic or ellipsometric characterization techniques.