Optical Measurement of Thermal Conductivity and Absorption Cross-Section of Gold Nanowires

Abstract

A thin film of Al0.94Ga0.06N doped with Er3+ is used to measure the heat dissipation from lithographically prepared gold nanowires (330 nm × 20 nm × 1.6 −13.2 μm) excited at 532 nm with a Nd:YAG continuous wave laser. A temperature image of the optically excited gold nanowire is processed from the relative peak intensities from Er3+ photoluminescence. The thermal profile along the nanowire is fit using an elementary heat transfer model with the thermal conductivity as an adjustable parameter. We observe a reduction in the temperature dependent thermal conductivity of the nanowires compared to the bulk value that is attributed to an increase in scattering from grain boundaries having an average diameter of 8 nm. Energy balance yields the absorption cross-section at 532 nm, when the laser polarization is aligned with the nanowire, as 1.4 ± 0.5 × 10–13 m2.