화학공학소재연구정보센터
Current Applied Physics, Vol.17, No.2, 174-180, 2017
Co and (Co,Mo) doping effects on the properties of highly reduced TiO2 anatase thin films
This work reports on the structural, optical, electrical and magnetic properties of Co:TiO2 and (Co,Mo):TiO2 anatase thin films grown onto (0001) sapphire substrates by Pulsed Laser Deposition in highly reducing conditions and at a low temperature of 350 degrees C. Undoped TiO2-delta as well as doped films with nominal compositions of Ti0.95Co0.05O2-delta. Ti0.94Co0.05M0.01O2-delta, and Ti0.92Co0.05Mo0.03O2-delta were studied. They all show similar microstructures, with smooth surfaces and RMS roughness values less than 0.5 nm. The optical band gap energies of the doped films are red shifted with respect to that deduced for the undoped TiO2-delta. The correlation between the band gaps and the Urbach energies of the films is discussed. All samples show semiconductor behavior with n-type conduction. The Co:TiO2 sample is ferromagnetic with a saturation magnetization of 1.3 mu(B)/Co, a high electrical conductivity of 123 S cm(-1) and a carrier density of 1.88 x 10(21) cm(-3) at room temperature. The ferromagnetic order of the Co:TiO2 system is suppressed when carriers are added by codoping with Mo. (C) 2016 Elsevier B.V. All rights reserved.