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

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, C-Ta=X-Ta/(X-Ta+X-Sn), varied from 0 to 7.13 at. %. For the five compositions studied, the lowest resistivity at room temperature was 2.01x10(-4) Omega cm at C-Ta=3.75% with charge carrier density and mobility of 1.27x10(21) cm(-3) and 24.5 cm(2)/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 Omega cm with charge carrier density and mobility of 1.31x10(18) cm(-3) and 28.1 cm(2)/V s obtained from Hall measurement. This study suggests that Ta is an excellent n-type dopant in SnO2. (C) 2001 American Institute of Physics.