INTERFACE POTENTIAL BARRIER HEIGHT AND LEAKAGE CURRENT BEHAVIOR OF PT(BA,SR)TIO3/PT CAPACITORS FABRICATED BY SPUTTERING PROCESS/

Variations of the leakage current behaviors and interface potential ba rrier height (Phi(B)) of rf-sputter deposited (Ba,Sr)TiO3 (BST) thin f ilms with thicknesses ranging from 20nm to 150 nm are investigated as a function of the thickness and bias voltages, The top and bottom elec trodes are dc-sputter-deposited Pt films. Phi(B), critically depends o n the BST film deposition temperature, postannealing atmosphere and ti me after the annealing. The postannealing under N-2 atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the Phi( B) from about 2.4eV to 1.6eV due to the oxidation. Phi(B) is not so de pendent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films sho w Schottky emission current and the thicker films show a mixed charact eristics with bulk and interface limited currents although the mechani sm is not clearly understood at this moment.