Temperature dependence of Raman enhancement induced by Au nanorods array

Temperature is an important factor in operation of plasmon-based devices in terms of optical enhancement and system stability. However, systematic study, especially for the experimental validation for the quantitative analysis of quantum efficiency in optical enhancement is still lack of investigation. In this work, the ordered array of Au nanorods is fabricated on silicon and the Raman enhancement of this SERS (Surface Enhanced Raman Scattering) substrate is systematically investigated experimentally for its temperature-dependent characteristics combined with physical explanations through electromagnetic simulations. The SERS substrate shows significant Raman enhancement of silicon signal over the temperature range of 293 to 424 K. It is found that as temperature is increased, Raman intensity of both bare silicon and SERS substrate is decreased with different slope of 0.0020/K and 0.0026/K, respectively. Besides, it is found that a temperature rise of 130 K results in a decrease of 10.2% in Raman enhancement ratio, agreeing well with calculated value (28.6%) of Raman enhancement factor as the maximum predicted range for perfect theoretical structure. The temperature dependence of Raman shift (the slope) does not differ much. However, the photon frequency of inelastic scattered light for both substrates is different at room temperature (0.35 cm−1) which is possibly attributed to the existence of residual stress in SERS substrate. The findings in this work are beneficial to understand the Raman enhancement at elevated temperatures, especially for applications in photovoltaic applications.