Measurement of the thermal conductance of silicon nanowires at low temperature

We have performed thermal conductance measurements on individual single-crystalline silicon suspended nanowires. The nanowires (130 nm thick and 200 nm wide) are fabricated by e-beam lithography and suspended between two separated pads on silicon on insulator substrate. We measure the thermal conductance of the phonon waveguide by the 3 omega method. The cross section of the nanowire approaches the dominant phonon wavelength in silicon which is of the order of 100 nm at 1 K. Above 1.3 K the conductance behaves as T-3, but a deviation is measured at the lowest temperature which can be attributed to the reduced geometry. (c) 2007 American Institute of Physics.