研究目的
To directly measure and characterize the hot electron flux from plasmonic Schottky nanodiodes, specifically investigating the intrinsic relation between hot electrons and localized surface plasmon resonance in Au nanoprism/TiO2 structures, and to understand the effects of field confinement and bias on hot electron generation and collection.
研究成果
The amplification of hot electron flux at the boundary of Au nanoprisms was directly probed using pc-AFM, demonstrating that field confinement during localized surface plasmon resonance excitation enhances hot electron generation. Reverse bias lowers the Schottky barrier, increasing hot electron collection. These findings provide fundamental insights for improving hot electron-based energy conversion devices.
研究不足
The study is limited by the lateral resolution of conventional spectroscopy methods, which cannot characterize local properties of each Schottky nanodiode. Imperfections in the self-assembly of polystyrene monolayers may lead to non-uniform arrays, affecting absorption spectra. The experiments focus on specific wavelengths and materials, and further research is needed for other metals or oxides.
1：Experimental Design and Method Selection:
The study employed photoconductive atomic force microscopy (pc-AFM) to simultaneously measure morphological variations and local photocurrent in individual Schottky nanodiodes. FDTD simulations were used to model field enhancements and absorbance. The thermionic emission equation was applied to analyze I-V curves for Schottky barrier height determination.
2：Sample Selection and Data Sources:
Triangular Au nanoprisms on n-type TiO2 substrates were fabricated using self-assembly nanosphere lithography with polystyrene nanospheres (460 nm diameter). UV-Vis spectroscopy and SEM/AFM were used for characterization.
3：List of Experimental Equipment and Materials:
Equipment includes a modified pc-AFM system (Agilent 5500), e-beam evaporator for metal deposition, OBIS series laser (Coherent) for illumination, TiN-coated AFM probe (CSG10, NT-MDT), fused silica prism, and ultrasonic cleaner. Materials include Au, Ti, TiO2, polystyrene nanospheres (Sigma-Aldrich), and ethanol.
4：Experimental Procedures and Operational Workflow:
Fabrication involved depositing Ti and Au films, annealing to form TiO2, creating nanopatterns with PS nanospheres, depositing Au, and removing PS. For pc-AFM, the sample was illuminated via a prism, and current mapping was performed under dark and light conditions at various wavelengths and biases. I-V curves were measured and fitted.
5：Data Analysis Methods:
Data analysis included fitting I-V curves to the thermionic emission equation, calculating external quantum efficiency (EQE), and performing FDTD simulations for field distribution and absorbance comparisons.
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