Fig. 4

Performance of higher-frequency (P0) MEMS resonators operated in vacuum. a Tuning curves of the P0 device at atmospheric pressure (100 kPa) environment at the onset voltage of 70 V (black) and at a very high voltage of 110 V (blue), and in a reduced pressure of 6.6 kPa at 50 V (orange) and 70 V (red). At 6.6 kPa, similar oscillation amplitudes can be achieved at much lower voltages and the Q factor of the oscillation is also improved as the tuning curves become much narrower. b Dependence of the oscillation amplitude on excitation voltage at 100 kPa and reduced pressures. Note that an amplitude of 10° can be achieved at lower voltages of 70 V (13.2 kPa) and 60 V (6.6 kPa). c DTW measurement using delay time scans at excitation voltage ranging from 50 to 70 V at a reduced pressure of 13.2 kPa. The DTW width reaches 0.5 ns at a moderate voltage of 70 V. The dependence of the DTW on the excitation voltage is shown in the inset to the figure, where the fit (line) assumes a linear relationship between the oscillation amplitude and the voltage. d Tuning curves of the P0 device operated in a pressure range from 59.2 kPa down to 6.6 kPa at an excitation voltage 60 V. e Time delay scans of the high-frequency device at 52.6, 26.3, and 6.6 kPa at 60 V. The DTW width reaches below 0.5 ns at 6.6 kPa even at this modest excitation voltage. f Dependence of DTW on the environmental pressure at 60 V. The DTW  width (circle) decreases almost one order of magnitude from 3.69 ns to 0.47 ns as the pressure drops from 52.6 to 6.6 kPa