Non-axisymmetric flexural vibrations of free-edge circular silicon wafers

• Non-axisymmetric flexural vibrations of circular silicon wafers are investigated.
• Vibration modes with azimuthal index 2• Measured loss factors are close to calculated thermoelastic loss for most of modes.
• The surface losses likely dominate for the modes with large angular index.
• Nonlinearity of the modes is also explored.

Non-axisymmetric flexural vibrations of circular silicon (111) wafers are investigated. The modes with azimuthal index 2⩽k⩽302⩽k⩽30 are electrostatically excited and monitored by a capacitive sensor. The splitting of the mode frequencies associated with imperfection of the wafer is observed. The measured loss factors for the modes with 6≲k≲266≲k≲26 are close to those calculated according to the thermoelastic damping theory, while clamping losses likely dominate for k≲6k≲6, and surface losses at the level of inverse Q  -factor Q−1≈4×10−6Q−1≈4×10−6 prevail for the modes with large k. The modes demonstrate nonlinear behavior of mainly geometrical origin at large amplitudes.