Efficient Photothermal Generation by Nanoscale Light Trapping in a Forest of Silicon Nanowires

Abstract

We experimentally investigate the photothermal conversion in disordered silicon nanowires (SiNWs) grown on a glass substrate by plasma-enhanced chemical vapor deposition. The temporal and spatial response under illumination of a 532 nm laser has been measured by means of an infrared (IR) thermocamera. Fast heat generation and adjustable temperature increase from a few tens up to ≈600 °C have been observed in a confined small region around the laser spot. The performing photothermal conversion is related to the efficient light trapping in SiNWs, providing enhanced absorption in the visible spectrum, and nonradiative recombination of the photogenerated carriers, typically occurring in Si. These findings combined with a low-cost, low-temperature, and large-area fabrication technology promote the disordered SiNWs as a flexible heat source well suited for applications in multiple fields including biology, precision medicine, gas detection, and nanometallurgy.