Surface effects and high quality factors in ultrathin single-crystal silicon cantilevers

Abstract

Surface effects in ultrathin single-crystal silicon cantilevers of 170 nm thickness, which are optically actuated mainly by the light pressure effect, are investigated under ultrahigh vacuum (UHV) condition. Annealing the cantilevers at 1000 °C for 30 s in UHV results in an over 1 order of magnitude increase of the quality factor (Q factor), up to about 2.5×105 for cantilevers of 30–90 μm in length. The improvement of Q factor was found to be associated with the deoxidization of the surface, as determined by x-ray photoelectron spectroscopy. These results suggest that the surface effects in the ultrathin cantilevers dominate their mechanical behavior. With the promising mechanical behavior, the cantilever can be easily actuated by a laser beam (beam size: about 300×100 μm2) with power down to less than 40 μW at a wavelength of 680 nm, corresponding to 480 nW, i.e., 1.64×1012 photons/s, irradiated on the cantilever surface (60×6 μm2). This provides a rather simple way to operate the ultrathin cantilevers dynamically in UHV. Atomic scale force resolution (4.8×10−17 N) at 300 K is also expected with these cantilevers.

Surface dissipation in nanoelectromechanical systems: Unified description with the standard tunneling model and effects of metallic electrodes

“…Among the different mechanisms affecting semiconductor-based NEMS the most important and difficult to avoid are i) clamping losses h L w t The height above the substrate is h. A schematic view of the surface is given, highlighting imperfections like roughness and adsorbates, which dominate dissipation at low temperatures. 33,34 , through the transfer of energy from the resonator mode to acoustic modes at the contacts and beyond to the substrate, ii) thermoelastic damping 35,36,37 and iii) friction processes taking place at the surfaces 38,39,40 . At low temperatures and for decreasing sizes the prevailing mechanism is the last one 6 , as indicated by the linear decrease of the quality factor of flexural modes with decreasing size (see fig.…”

“…At low temperatures and for decreasing sizes the prevailing mechanism is the last one 6 , as indicated by the linear decrease of the quality factor of flexural modes with decreasing size (see fig. [2]), or the sharp increase of Q when the resonator is annealed 38,41 . Excitation of adsorbed molecules, movement of lattice defects or configurational rearrangements absorb irreversibly energy from the excited eigenmode and redistribute it among the rest of degrees of freedom of the system.…”

Low-concentration mechanical biosensor based on a photonic crystal nanowire array

“…One of the mechanical modes possesses highest quality factor up to 3.2 × 10 5 , as shown by the frequency response plot in Figure 3c . Th e high quality factor of the resonator (in vacuum 0.1 mTorr) might be due to the reduced surface loss 24 and clamping loss 25 , through proper Si surface high-temperature annealing treatment processes and the induced tensile stress to the Si fi lm, respectively ( Supplementary Discussion ). Measured standing-wave vibration amplitude 2D mapping pattern of this mode was shown in Figure 3d .…”

Sensitivity Analysis of a Proposed Novel Opto-Nano-Mechanical Photodetector for Improving the Performance of LIDAR and Local Optical Sensors

“…It was shown that submK cooling is feasible with this technique. Optical actuation of cantilevers by light has already been demonstrated [5,6]. In our case, the cantilever functions both as a high-frequency detector and as a high-Q filter.…”