Reduction of leakage current by Co doping in Pt/Ba0.5Sr0.5TiO3/Nb-SrTiO3 capacitor

Effect of Co doping on leakage current has been investigated in capacitor consisting of Ba0.5Sr0.5Ti1-xCoxO3 (BSTC, x=0, 0.002, 0.010) thin film, Pt top electrode, and Nb-doped SrTiO3 (STON) bottom electrode. Co doping remarkably decreases the leakage current in BSTC thin film, such as from 9x10(-7) A in undoped thin film to 8x10(-11) A in 1.0 at. % Co-doped BSTC thin film at bias voltage of 6 V. In the case of the Pt electrode positively biased, the leakage current shows space-charge-limited-current behavior. The trap-filled-limit voltage and the calculated trapped electron density increase with Co concentration in BSTC thin film. The mechanism of the reduction of the leakage current by Co doping is discussed. (C) 2004 American Institute of Physics.