Effect of surface roughness on thermal conductivity of silicon nanowires

Reducing the thermal conductivity of nanowires may enhance their already exciting efficiency of thermoelectric energy conversion. Using molecular dynamics simulations, we demonstrate that the thermal conductivity of silicon nanowires could be significantly decreased by patterning (or etching) induced roughness of the nanowire surfaces. The type, amplitude, and wavelength of the surface roughness all have profound effects, and the thermal conductivity could be reduced more when the wavelength is smaller or the amplitude is larger. Such an effect of roughness on the thermal conductivity is furthermore found to be coupled with the effects of nanowire cross-sectional size and length. Typically, the roughness effect is more prominent in longer and larger nanowires.