Investigation of Local Photoconductivity of ZrO<sub>2</sub>(Y) Films with Embedded Au Nanoparticles by Conductive Atomic Force Microscopy
The local transverse photoconductivity of ultrathin (~4 nm) ZrO<sub>2</sub>(Y) films with embedded single-layered arrays of Au nanoparticles (~2 nm in diameter) was studied by conductive atomic force microscopy. The ZrO<sub>2</sub>(Y) films with Au nanoparticles were formed on glass substrates with transparent conductive indium-tin oxide sublayers using layer-by-layer magnetron deposition followed by annealing. Peaks observed in the optical absorption spectra of the samples at the wavelength λ ≈ 660 nm were attributed to the collective plasmon resonance in dense arrays of Au nanoparticles. The photocurrent between the microscope probe and the indium-tin oxide sublayer was measured during the photoexcitation of the contact between the probe and the sample surface thorough the transparent substrate by radiation of a semiconductor laser diode at the plasmon resonance wavelength. The increase in current through the probe of the atomic force microscope under photoexcitation was attributed to the photon-assisted emission of electrons from the Au nanoparticles into the conduction band of ZrO<sub>2</sub>(Y) in a strong electric field applied between the probe and indium-tin oxide sublayer under plasmon resonance conditions.