Effects of oxygen pressure and Mn-doping on the electrical and dielectric properties of Bi5Nb3O15 thin film grown by pulsed laser deposition

Abstract

Bi5Nb3O15 (B5N3) thin films grown at temperatures above 500 degrees C developed a crystalline B5N3 phase that decomposed into a BiNbO4 phase in the film grown at 700 degrees C, probably due to Bi2O3 evaporation. The leakage current density of the B5N3 film grown at 200 degrees C under an oxygen pressure (OP) of 100 mTorr was high at approximately 6.3 x 10(-7) A cm(-2) at 0.2 MV cm(-1), with a small breakdown field of 0.24 MV cm(-1) due to the presence of intrinsic oxygen vacancies. The electrical properties of the B5N3 films improved with increasing OP during the growth but the dielectric constant (epsilon(r)) decreased. The Mn-doping also improved the electrical properties of the B5N3 films grown under low OP by producing doubly ionized oxygen vacancies, which decreased the number of the intrinsic oxygen vacancies. Furthermore, the Mn-doping increased the epsilon(r) value of the B5N3 film, confirming the effectiveness of such doping in improving both the electrical and the dielectric properties of the B5N3 film. In particular, the 5.0 mol% Mn-doped B5N3 film grown at 200 degrees C under an OP of 100 mTorr exhibited a low leakage current density of 7.9 x 10-8 A cm(-2) at 0.2 MV cm(-1) and a large breakdown field of 0.4 MV cm(-1) with a high epsilon(r) of 64.