'High Q' Nanowires May Be Practical Oscillators -- COMPAMED Trade Fair

'High Q' Nanowires May Be Practical Oscillators


"We think the most interesting thing about these wires is the very high quality factor observed for such a small object", says NIST researcher and co-author Kris Bertness, who grew the nanowires.

Researchers at NIST and the University of Colorado at Boulder report high Q factors in wires that are 30 to 500 nanometres in diameter and 5 to 20 micrometres long, vibrating between 400,000 and 2.8 million times per second. The nanowires vibrated when placed on a piezoelectric device stimulated by an electrical signal. The nanowires also oscillated when excited directly by an electron beam, apparently due to the GaN material’s intrinsic piezoelectric ability to covert voltage to mechanical force.

Q measures the damping of oscillations in a mechanical system as a function of frequency - the higher its Q, the longer a bell rings after being struck. Ordinarily, Q factors of mechanical resonators tend to drop as their diameters shrink. But GaN nanowires have a number of properties that may boost their Q and make them suitable as practical oscillators. They have extremely flat and smooth surfaces. GaN also has a resonant frequency similar to silicon but is less susceptible to some sources of “noise.”

Finally, GaN has high heat capacity and thermal conductivity, reducing sensitivity to temperature fluctuations. Another practical advantage is that NIST’s GaN nanowires are grown on silicon, making them compatible with existing microelectronics processing methods.

