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Temperature-dependent mechanical-resonance frequencies and damping in ensembles of gallium nitride nanowires



Kristine A. Bertness, Norman A. Sanford, J. R. Montague, H.S. Park, Victor M. Bright, Charles T. Rogers


We have measured singly clamped cantilever mechanical-resonances in ensembles of as-grown gallium nitridenanowires (GaN NWs), from 12 K to 320 K. Resonance frequencies are approximately linearly dependent on temperature near 300 K with relative shifts of 40 {plus or minus} 20 ppm/K, consistent with temperature-dependent elastic moduli. Below 100 K, we find that some GaN NWs have mechanical quality factors well above 400 000, at mechanical resonance frequencies near 1 MHz. We also observe a correlation between increased amplitude of dissipation and increased temperature dependence of resonance frequencies. The microwavehomodyne detection technique we use is simple, allows for the investigation of as-grown or processed NWs, and is sensitive enough to observe the thermal motion of individual NWs while providing for the simultaneous measurement of large ensembles of NW mechanical resonances.
Applied Physics Letters
Created October 22, 2012, Updated November 10, 2018