Structural and electrical properties of Bi2O3-Nb2O5 thin films grown at low temperatures by pulsed laser deposition

Abstract

The dielectric constant (epsilon(r)) of the films grown at 100 degrees C increased as the beam energy density increased and a saturated value of 80 was obtained for the film grown under 6.0 J cm(-2). The larger epsilon(r) value was attributed to the increased amount of nano-sized Bi3NbO7 crystals. The epsilon(r) values also increased with the beam energy density for films grown at 300 degrees C and a very high epsilon(r) value of 135.6 with a low loss of 3.0% at 100 kHz was obtained for the film grown at 300 degrees C under a beam density of 3.0 J cm(-2). The crystalline BiNbO4 phase developed, but the amount of Bi3NbO7 crystals decreased as the beam energy density increased, indicating that the increased epsilon(r) values of the films grown at 300 degrees C could be due to the formation of the crystalline BiNbO4 phase. The electrical properties of the films grown at 300 degrees C under a beam density of 3.0 J cm(-2) were considerably influenced by the oxygen partial pressure (OPP) during annealing. The film annealed at 300 degrees C under a 50.0 torr OPP exhibited a low leakage current density of 5.4 x 10(-9) A cm(-2) at 0.3 MV cm(-1) with a relatively high breakdown field of 0.4 MV cm(-1). (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.