Grain size control of (111) polycrystalline 3C-SiC films by doping used as folded-beam MEMS resonators for energy dissipation

Abstract

This manuscript presents an analysis of the energy dissipation mechanisms in microelectromechanical systems (MEMS)-based, flexural-mode polycrystalline silicon carbide (SiC) lateral resonators. The grain structure with columnar (111) polycrystalline 3C-SiC was unintentionally and intentionally doped by low pressure chemical vapor deposition (LPCVD). Device testing was conducted using a transimpedance amplifier-based circuit to measure the total quality factor. It was found that thermoelastic damping (TED) in SiC MEMS-based lateral resonators contributes only in a small way to the overall energy dissipation in these devices. In contrast, the dominant material property appears to be the grain size for lightly and heavily doped film, with smaller grain sizes correlating to higher solid internal losses. The data suggest that conductivity does not play a direct role in determining the quality factor despite the fact that an electrical measurement technique was used. In fact, the lowest quality factors were associated with the lowest resistivities.

Physical loss mechanisms for resonant acoustical waves in boron doped poly-SiGe deposited with hydrogen dilution

“…The source of the losses can be both extrinsic or intrinsic to the material. Some research that was performed for polycrystalline materials include the work of Chang and Zorman, 19 who recently presented results for polycrystalline silicon-carbide ͑poly-SiC͒. Several extrinsic loss mechanisms have been identified and dealt with through careful design and packaging, e.g., anchor losses 9,10 and gas damping.…”

Solid Internal Energy Dissipation of 3C Single-Crystal Silicon Carbide Micromechanical Resonators by Heterojunction Growth on Silicon

“…This result agrees with the previous result, suggesting that the quality factor decreases as electrical resistivity decreases, since a higher doping concentration can lower SiC crystallization, and thus lead to a smaller grain size. (29) In other words, the electrical loss is not a dominant factor in determining quality factor. This, despite the fact that the Qs were obtained by electrical measurement throughout the measurement.…”

Growth Mechanism and Defects of <111>‐Oriented β‐SiC Films Deposited by Laser Chemical Vapor Deposition

“…However, most of these efforts are taken to avoid the planar defects in (111) plane by growing <100>‐oriented β‐SiC. In theory, the β‐SiC with {111} planar defects, such as twin or anti‐phase, has a lower energy than the nondeficient β‐SiC; hence, these planar defects are commonly existed in β‐SiC . Recently, three efficient methods: Switch‐Back‐Epitaxy (SBE), Inverted Silicon Pyramids (ISP), and Pendeo‐Epitaxial‐Growth (PEG) for growing <100>‐oriented β‐SiC with less defects have been developed.…”