Structural correlations for increased FOM in Pb doped Zn2SnO4 nanostructured films for applications as transparent electrode

Abstract

This work reports the detailed analysis of the structure and optoelectronic properties of spin coated Zn2−xPbxSnO4 nanostructured films. XRD studies reveal the polycrystalline cubic inverse spinel structure while Raman spectra show the dominance of T2 g(3) mode and decrease in intensity of A1 g mode with Pb doped ZTO films. X-ray photoelectron spectroscopy substantiates the dominance of atom in multiple charge states and their possible substitutions in the host lattice. The maximum average transparency of 87% in 400–650 nm spectral region for x = 0.08 sample while the decrease in optical gap from 4.32 to 4.14 eV with minimal value of 4.04 eV for x = 0.04 is found. The refractive index at 500 nm is calculated using Swanepoel’s method and found to decrease from 1.72 for ZTO and 1.59 for x = 0.08 sample. The carrier concentration increases from 1018 cm−3 for ZTO to 1020 cm−3 for x = 0.08 sample. The minimal value of electrical resistivity of 2.17 × 10−3 Ω-cm and maximal Haacke’s Figure of merit (FOM) of 1.1 × 10−3/ Ω is obtained for x = 0.08. These results are significant advancement to the development of ZTO based transparent conductors for highly efficient futuristic optoelectronics and photovoltaic devices.