Long term stability and quality factors of degenerately n-type doped silicon resonators

Abstract

Effect of degenerate doping on the long term stability and quality factors of silicon resonators was studied. The long term stability of electrostatically coupled tuning fork and width extensional mode resonators was found to be better than 1 ppm during a measurement spanning 220 days. Resonators were phosphorus doped to a carrier concentration of 4.1 × 10 19 cm −3 . Quality factors of~10-MHz Lamé mode resonators on wafers doped up to a concentration of 7.5 × 10 19 cm −3 were found to range from 900,000 to 1,500,000, which is comparable to that reported for similar resonators with moderate doping. The results indicate that the effect from heavy phosphorus doping on resonator stability or on silicon intrinsic losses is low at the studied doping levels.

A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

“…19 Secondly, silicon is a material being commonly used in electronics, photonics, MEMS. For MEMS resonator field, it is used to fabricate silicon-on-insulator (SOI) MEMS resonators, [20][21][22] thin-film piezoelectric-on-silicon MEMS resonators 12,[23][24][25] or PnC-based MEMS resonators. 17,18,26 In these resonators, the substrate as well as support tethers are almost made of the same silicon material.…”

“…Thirdly, the technique doping a dopant into silicon has been employed in many areas, e.g, in polycrystalline Si thin films phononic crystal nanopatterning for thermoelectric applications 27 or temperature-induced frequency stability of silicon-based MEMS resonators. 23,24,28 Obviously, the pattern of air hole in PnC-based MEMS resonators can reduce thermal conductance. 29 However, this doping mechanism can be employed for any type of silicon-based MEMS resonators to obtain a turnover point 23 which avoids to drift the operating frequency of the resonators.…”