Transparent conducting oxide thin films of Cd 2SnO 4 prepared by RF magnetron co-sputtering of the constituent binary oxides

Abstract

Thin films of cadmium tin oxide (Cd 2SnO 4) have been deposited on glass substrates by RF magnetron co-sputtering from cadmium oxide (CdO) and tin oxide (SnO 2) targets in an Argon ambient. Co-sputtering offers a means to control the atomic stoichiometry of Cd 2SnO 4, which influences the material's electro-optical and structural properties. The Cd 2SnO 4 films were deposited at room temperature and subsequently subjected to a heat treatment in inert or reducing (H 2) ambient. The as-deposited films were amorphous, and became polycrystalline after annealing at high temperatures. Using this method, Cd 2SnO 4 films with a Hall mobility of 32.3 cm 2 V −1 s −1 and a carrier concentration of 7.40×10 20 cm −3 corresponding to a resistivity of 2.07×10 −4 Ω cm have been prepared. The films exhibited average optical total transmission in excess of 90% in the visible region. The optical bandgap was found to be in the range of 2.97–3.18 eV, depending on post deposition treatment.