(ANI): This is the highest frequency achieved to date in silicon, with a quality factor close to 10,000.
The quality factor, which is, among other things, a measure of the amount of stored energy in an oscillator, usually decreases with increasing frequency.
The new device consists of a silicon bar set into vibration by a process called "dielectric transduction." An alternating voltage is applied to a rod electrode separated by an insulator. The attractive forces between electric charges of the electrode and the bar create mechanical vibrations that travel along the bar from one end the other of it, like sound waves in a flute or a pipe of an organ.
Previously, researchers had used an air gap as the dielectric. Substituting this for a solid dielectric is easier to obtain the oscillations at higher frequencies, but the solid dielectric damps vibrations and reduces power transmission efficiency of the oscillator.
Dana Weinstein found by mathematical analysis that efficiency could be increased by moving the dielectric layers from the ends of the bar down the middle. The ideal positions are two-thirds of distance from the center the bar towards the end. These locations are the points of maximum stress when there is vibration.
The resulting device is a silicon bar of 8.5 microns long, 40 meters wide and 2.5 thick, divided by two dielectric layers of silicon nitride only 15 nanometers thick.
According to the researchers, the method could produce resonators with frequencies exceeding 10 GHz.
The quality factor, which is, among other things, a measure of the amount of stored energy in an oscillator, usually decreases with increasing frequency.
The new device consists of a silicon bar set into vibration by a process called "dielectric transduction." An alternating voltage is applied to a rod electrode separated by an insulator. The attractive forces between electric charges of the electrode and the bar create mechanical vibrations that travel along the bar from one end the other of it, like sound waves in a flute or a pipe of an organ.
Previously, researchers had used an air gap as the dielectric. Substituting this for a solid dielectric is easier to obtain the oscillations at higher frequencies, but the solid dielectric damps vibrations and reduces power transmission efficiency of the oscillator.
Dana Weinstein found by mathematical analysis that efficiency could be increased by moving the dielectric layers from the ends of the bar down the middle. The ideal positions are two-thirds of distance from the center the bar towards the end. These locations are the points of maximum stress when there is vibration.
The resulting device is a silicon bar of 8.5 microns long, 40 meters wide and 2.5 thick, divided by two dielectric layers of silicon nitride only 15 nanometers thick.
According to the researchers, the method could produce resonators with frequencies exceeding 10 GHz.
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