Effect of Sb doping on structural and photoelectric properties of SnO2 thin films

Abstract

Sb-doped SnO2 (ATO) thin films were synthesized via the sol–gel dip-coating method on glass substrates. The XPS and XRD spectra showed that Sb atoms were successfully incorporated into the SnO2 lattice and mostly existed in the form of Sb5+ (~ 90%) in 1 at.% ATO thin films annealed in air and further annealed in vacuum. The transmittance spectra revealed that the average transmittance was more than 75% at the wavelength range of 325–700 nm. The average sheet resistancewas 14.05 kΩ/□ in 1 at.% ATO thin films annealing in air and much less than undoped SnO2. The electric property was better when ATO thin films were further annealing vacuum compared to annealing in air. The average sheet resistance and resistivity of 1 at.% ATO thin films were 2.42 kΩ/□ and 0.035 Ω cm, respectively. The PL showed that electrons transition from a shallow level of VO to the minimum level of conduction band (CBM) increased with increasing of Sb3+ ions. The maximum level of valence band (VBM) and CBM level positions were mainly affected by Sb3+ and Sb5+ energy levels after air annealing, respectively. The behavior of surface carrier transport was investigated after further vacuum annealing. The CBM–VBM level position mainly was affected by VO energy level after further vacuum annealing. It was further proved by the Hall carrier concentration and the electrochemical impedance spectroscopy (EIS).