Phonon scattering mechanisms in suspended nanostructures from 4 to 40 K
We have developed specially designed semiconductor devices for the measurement of thermal conductance in suspended nanostructures. By means of a novel subtractive comparison, we are able to deduce the phonon thermal conductance of individual nanoscale beams of different geometry and dopant profiles. The separate roles of important phonon scattering mechanisms are analyzed and a quantitative estimation of their respective scattering rates is obtained using the Callaway model. Diffuse surface scattering proves to be particularly important in the temperature range from 4 to 40 K. The rates of other scattering mechanisms, arising from phonon-phonon, phonon-electron, and phonon-point defect interactions, also appear to be significantly higher in nanostructures than in bulk samples.
Additional Information© 2002 The American Physical Society Received 12 February 2002; published 9 July 2002 We gratefully acknowledge support from the NSF under Grant No. DMR-9705411 and from DARPA/MTO/MEMS under Grant No. DABT63-98-1-0012.
Published - FONprb02.pdf