Investigation into the Regulation of Ag NPs/ZnO NRs/GaN Heterostructure SERS Substrate via Pyroelectric Effects

Heterostructures have emerged as promising contenders for surface-enhanced Raman scattering (SERS) applications. Nevertheless, the construction of a composite SERS substrate with well-matched energy levels persists as a challenge, primarily due to the restricted selection of SERS-active materials. In this study, we successfully synthesized a Ag nanoparticles (NPs)/ZnO nanorods (NRs)/GaN heterojunction featuring type II staggered energy bands, which provides an outstanding platform for efficient SERS detection. Moreover, considering that both ZnO and GaN are pyroelectric semiconductor materials, the pyroelectric potential generated at the ZnO and GaN heterojunctions improves energy level matching. This, in turn, promotes charge transfer within the composite structure and substantially enhances the chemical enhancement of SERS. Under the modulation of pyroelectricity, the SERS signal intensity of rhodamine 6G (R6G) increased by approximately 15-fold, and the detection limit decreased by at least 2 orders of magnitude. Additionally, the substrate exhibited the capability to detect pollutants, such as 20 nm nanoplastics and thiram, indicating its significant potential for environmental monitoring.