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

摘要

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.