Structural, electrical, and optical properties of spin-coated Bi:SnO2 transparent conducting oxide thin films

Abstract

We synthesized different concentrations of Bi (1, 2, 3, 4, and 5 at %) doped SnO2 (Bi:SnO2) thin films using the sol-gel spin coating method. The XRD studies confirmed that all deposited films exhibit polycrystalline tetragonal rutile structure. Raman spectra displayed three fundamental bands at 473, 631, and 774 cm−1, which correspond to the Raman modes Eg, A1g, and B2g. The average transmittance is above 76% for all films. The optical bandgap energy increased from 3.91 eV for pure SnO2 to 4.22 eV for 3 at% Bi:SnO2 film and slightly decreased for 4 and 5 at % Bi:SnO2 films. The sheet resistance (Rsh) and resistivity (ρ) values decreased up to 38.8 Ω/□ and 1.62 × 10−3 Ω-cm, respectively, in 3 at % Bi: SnO2 thin film, and then slightly increased for 4 and 5 at % Bi: SnO2 films.