Optical and electrical properties of Nd‐doped BiFeO 3 thin films and heterostructures

High quality BiFeO 3 (BFO) and Bi 0.9 Nd 0.1 FeO 3 (BNFO) thin films ( d = 150‐350 nm) were grown at 650‐750°C by RF sputtering on dielectric (SrTiO 3 ; ZrO 2 ) and conducting (Nb‐doped SrTiO 3 (100); n‐type Si) substrates. A direct band gap at 2.57 eV and 2.62 eV (at T =295 K) have been estimated for the BFO/YSZ and BNFO/YSZ films from optical transmittance spectra while an unset of weak absorption has been indicated for the films at 2.20 eV. Transverse electrical transport of the (BFO, BNFO)/(STON, Si) heterostructures revealed nonlinear current versus voltage behavior and clearly defined rectifying properties. Schottky junction model has been applied for the heterojunctions at T =300 K although complicated shape of I‐U curves demonstrated increasing role of space charge limited current with T decreasing down to 78 K. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)