Conduction mechanism and switchable photovoltaic effect in (111) oriented BiFe0.95Mn0.05O3 thin film
Résumé
Epitaxial 200 run BiFe0.95Mn0.05O3 (BFO) film was grown by pulsed laser deposition (PLD) on (1 1 1) oriented SrTiO3 substrate buffered with a 50nm thick SrRuO3 electrode. The BFO thin film shows a rhombohedral structure and a large remnant polarization of Pr = 104 mu C cm(-2). By comparing I(V) characteristics with different conduction models we reveal the presence of both bulk limited Poole-Frenkel and Schottky interface mechanisms and each one dominates in a specific range of temperature. At room temperature (RD and under 10 mW laser illumination, the as grown BFO film presents short-circuit current density (J(sc)) and open circuit voltage (V-oc) of 2.25 mA cm(-2) and -0.55 V respectively. This PV effect can be switched by applying positive voltage pulses higher than the coercive field. For low temperatures a large V-oc value of about -4.5 V (-225 kV cm(-1)) is observed which suggests a bulk non-centrosymmetric origin of the PV response.