“…ZnO nanorods (ZnO-NRs) have been considered as promising building blocks for various applications such as light-emitting diodes, − organic/inorganic solar cells, − and spectroscopy signal enhancement platforms − due to their wide bandgap semiconductor with 60 meV binding energy at room temperature and a waveguide effect, where the hexagonal structures of ZnO-NRs can be attributed to the Fabry–Perot resonators (FPRs) with the end faces as reflecting mirrors . In the last few decades, the hydrothermal process has been widely appreciated comparing with other synthesis techniques such as the vapor–solid (VS) method, , vapor–liquid–solid (VLS) method, − and metal–organic chemical vapor deposition (MOCVD) , because of its low-temperature process ( T ≈ 95 °C), controllable diameter and position via seed crystals, and cost-effectiveness. − These allow us to integrate hydrothermal ZnO-NRs with various materials on organic substrates for biosensors, biomedical analysis, and flexible nanoelectronic devices. − A homogeneous ZnO seed layer has been frequently employed to control the morphological properties (e.g., density, diameter, and length) of ZnO-NRs. ,,− However, such a semiconducting characteristic of the ZnO homo-seed layer may not be applicable for electrical devices when direct low resistance electrical contact between the ZnO-NRs and the substrates is unavoidably required. , The directly contacted interface between the ZnO-NRs and noble metals, e.g., gold (Au), , silver (Ag), ,,,, and copper (Cu), is not only robust for electrical applications but also for the spectroscopy signal enhancement platform due to the localized surface plasmon resonance (LSPR) and high-reflectance properties of the noble metals and waveguide effect of ZnO-NRs. ,, ...…”