High quality factor resonance at room temperature with nanostrings under high tensile stress

Quality factors as high as 207 000 are demonstrated at room temperature for radio-frequency silicon nitride string resonators with cross sectional dimensions on the scale of 100 nm, made with a nonlithographic technique. A product of quality factor and surface to volume ratio greater than 6000 nm ^-1 is presented, the highest yet reported. Doubly clamped nanostring resonators are fabricated in high tensile-stress silicon nitride using a nonlithographic electrospinning process. We fabricate devices with an electron beam process, and demonstrate frequency and quality factor results identical to those obtained with the nonlithographic technique. We also compare high tensile-stress doubly clamped beams with doubly clamped and cantilever resonators made of a lower stress material, as well as cantilever beams made of the high stress material. In all cases, the doubly clamped high stress beams have the highest quality factors. We therefore attribute the high quality factors to high tensile stress. Potential dominant loss mechanisms are discussed, including surface and clamping losses, and thermoelastic dissipation. Some practical advantages offered by these nanostrings for mass sensing are discussed.