Optothermal characterization on thermal diffusivity, carrier diffusion and recombination properties of annealed thin Au film deposited on Si substrate

Abstract

In this work, an optothermal wave characterization based on the photoacoustic (PA) technique was first implemented to investigate the thermal and carrier transport properties of Au thin film layer deposited on Si wafers (Au/Si) annealed at different temperatures. The XRD pattern showed that a metastable gold (Au) silicide of Au81Si19 phase formation was traced at annealing temperature of 330 oC and this structure disappeared when the temperature was further elevated up to 370 oC. The result showed that the PA signal obtained for Au/Si structure was lower than the pure Si wafer. The thermal and carrier transport properties of Si and Au/Si were elucidated from the fitting of PA signalphase relation. From the result, the thermal diffusivity and surface recombination velocity of Au/Si increased with shorter recombination lifetime as the raise of annealing temperature. Nonetheless, as the temperature approaches 370 oC, the surface recombination and thermal transport process diminishes, which may be ascribed to the rupture of silicide clusters.