Electrical and optical properties of transparent conducting ZnO:Al/AgNP multilayer films

In this work, zinc oxide thin films doped with Al were prepared using sol-gel deposition technique. Fabricated films were up 1 µm thick and contain several layers of ZnO:Al deposited on quartz substrate. The films had prevalent (001) growth orientation. The resistivity of the films was reduced significantly after annealing in vacuum (10^-5 Pa) at 650 °C and achieved 0.3 Ω·сm. The optical properties of ZnO:Al/AgNP films were tested. The extinction spectra of the films showed the shift of AgNP plasmon resonance with respect to the position being characteristic to silver nanoparticles on fused quartz substrate. The optical radiation action increased the conductivity of ZnO:Al/AgNP films 5 times. An observation of photocurrent was associated with the excitation of plasmon resonance in nanoparticles and was described by the mechanism of "hot" electrons injection in the conduction band of ZnO: Al.