Carrier Density-Dependent Localized Surface Plasmon Resonance and Charge Transfer Observed by Controllable Semiconductor Content

We discuss how the controllable carrier influences the localized surface plasmon resonance (LSPR) and charge transfer (CT) in the same system based on ultraviolet–visible and surface-enhanced Raman scattering (SERS) measurements. The LSPR can be easily tuned from 580 to 743 nm by changing the sputtering power of Cu2S in the Ag and Cu2S composite substrate. During this process, surprisingly, we find that the LSPR is proportional to the sputtering power of Cu2S. This observation indicates that LSPR can be accurately adjusted by changing the content of the semiconductor, or even the carrier density. Moreover, we characterize the carrier density through the detection of the Hall effect to analyze the Raman shift caused by CT and obtain the relationships between them. These fundamental discussions provide a guideline for tunable LSPR and the investigation of CT.