Improved conductivity and mechanism of carrier transport in zinc oxide with embedded silver layer

The effects of an embedded silver layer on the electrical and optical properties of zinc oxide (ZnO)/silver (Ag)/zinc oxide (ZnO) layered composite structures on polymer substrates have been investigated. We have engineered transparent conducting oxide structures with greatly improved conductivity. Optical and electrical properties are correlated with Ag thickness. Film thicknesses were determined using Rutherford backscattering spectrometry. Hall effect, four-point probe, and UV-Vis spectrophotometer analyses were used to characterize electrical and optical properties. The results show that carrier concentration, mobility, and conductivity increase with Ag thickness. Increasing Ag thickness from 8to14nm enhances sheet resistance and resistivity by six orders of magnitude. The optical transmittance of the composite structure decreases when compared to a single ZnO layer of comparable thickness. However, a composite with 12nm of Ag provides conductivity and transmittance values that are acceptable for optoelectronic devices. We describe of the influence of Ag thickness on electrical and optical properties of the ZnO∕Ag∕ZnO composite and propose a conduction mechanism for this system.