Oxygen pressure and Mn-doping effects on the structure and leakage current of Bi(6)Ti(5)TeO(22) thin film

Abstract

Te ions existed as Te(6+) in the Bi(6)Ti(5)TeO(22) (BTT) film grown at 300 degrees C under a high oxygen pressure (OP) of 80.0 Pa and contributed to the formation of the crystalline BTT phase after subsequent annealing at 600 degrees C. However, for the BTT film grown under a low OP of 53.3 Pa (or 9.33 Pa), Te(6+) ions, were converted to Te(4+) ions, which induced the phase transition of the BTT phase to the pseudo-Bi(4)Ti(3)O(12) and pseudo-Bi(2)Ti(2)O(7) phases after annealing at 600 degrees C. The leakage current density decreased with increasing OP during the growth due to the decreased number of oxygen vacancies. The breakdown voltage also improved with increasing OP during the deposition. The Mn ions introduced in the BTT films by Mn doping existed as Mn(2+) or Mn(4+) and acted as the acceptors. This Mn doping to 10 mol % also reduced the leakage current density and increased the breakdown voltage by decreasing the number of intrinsic oxygen vacancies. (C) 2008 The Electrochemical Society.