Thermal stability study of niobium doped SnO2 thin film for transparent conducting oxide application

Abstract

Abstract The temperature-dependent electrical property of niobium (Nb) doped SnO2 (NTO) films were investigated for optoelectronic applications. Temperature-dependent electrical properties of the films show two different conduction processes between 200 °C and 450 °C, as calculated by Arrhenius approaches. In the metal oxide system increase in temperature may be possible to reduce oxygen formation energy, this leads to create more oxygen vacancies. The conductivity of NTO film increased up to 250 °C due to thermally generated free carrier concentration. The electrical conductivity decreased beyond 250 °C due to decreased free carrier mobility because of rapid defect formation at higher temperatures. Generally, free carrier collision, charge carrier absorption by native oxygen, and ionized impurity scattering are predominant factors which affect the mobility of free carrier at different temperature ranges. More importantly, the NTO film deposited at 1.5 wt % of Nb doping concentration in SnO2 system shows better optical transmittance and electrical resistivity than other films. The maximum resistivity of 6.45 × 10−4 Ω cm, sheet resistance of 25.94 Ω/□, optical transmittance of 82%, and thermal stability of 250 °C indicates the suitability of NTO thin films for potential applications in optoelectronic devices.