Electrical properties of Ta-doped SnO2 thin films prepared by the metal–organic chemical-vapor deposition method

Abstract

Undoped and Ta-doped SnO2 (Sn1−xTaxO2) thin films were prepared on Corning 7059 glass substrates by the metal–organic chemical-vapor deposition method. The relative amount of Ta, CTa=XTa/(XTa+XSn), varied from 0 to 7.13 at. %. For the five compositions studied, the lowest resistivity at room temperature was 2.01×10−4 Ω cm at CTa=3.75% with charge carrier density and mobility of 1.27×1021 cm−3 and 24.5 cm2/V s, respectively. In microstructural investigation, 3.75% Ta-doped film maintains a growth pattern of initial stage growth while 7.13% Ta-doped film has a high population of small grains at the interface, which results in large grains through competitive growth. The resistivity of the undoped film was 0.17 Ω cm with charge carrier density and mobility of 1.31×1018 cm−3 and 28.1 cm2/V s obtained from Hall measurement. This study suggests that Ta is an excellent n-type dopant in SnO2.