Talk Title: Recent Progress in Semiconductor-enhanced Raman Scattering
In 1982 Yamada et al. succeeded in observing SERS of pyridine on the surface of NiO and TiO2. This might be the first observations of semiconductor SERS. Semiconductor-enhanced Raman scattering was looked again after 2000. For example, B. Zhao cooperated with Lombardi et al. reported semiconductor-enhanced Raman scattering for metal oxides, metal tellurides, metal sulfides, and so on. They proposed a clear CT model to explain the enhanced Raman on semiconductor materials. There are several kinds of semiconductor materials for enhanced Raman scattering. Metal oxides such as TiO2 and ZnO are representative ones. The enhancement factor of semiconductor-enhanced Raman scattering is typically 103-108.
The advantages of semiconductor-enhanced Raman scattering are summarized as follows:
(1) Semiconductor materials have excellent high chemical and thermal stability. Thus, they can avoid the problem of signal reproducibility caused by substrate oxidation.
(2) Semiconductor materials have superb surface modifiability. In contrast to metal materials, most of common functional groups can be directly adsorbed on semiconductor materials surfaces.
(3) Semiconductor materials have good biocompatibility.
(4) Semiconductor materials have a variety of species. The SERS enhancement mechanisms of semiconductors are concerned both with electromagnetic and chemical enhancement. Metals show LSPR due to high-density of free electrons, on the other hand, the semiconductor materials primarily achieve electromagnetic enhancement through light-trapping and subwavelength-focusing capabilities, as well as morphology-dependent resonances such as Mie resonance.