Effect of top metal contact on the ferroelectric photovoltaic response of BFO thin film capacitors

Present work reports the photovoltaic (PV) effect in different metal top electrodes decorated multiferroic BFO thin films. Polycrystalline BFO thin film has been deposited on Platinum (Pt) coated silicon substrates successfully through Pulsed laser deposition (PLD) technique. Different Metal top electrodes (Au, Cu, Ag, and Al) of 200 μm diameter were deposited on BFO thin films using thermal evaporation technique and their influence on ferroelectric and photovoltaic properties including Jsc -short circuit current, Voc -open circuit voltage and Ion/Ioff has been investigated. Variation in photovoltaic properties with different metal contacts has been related to the leakage current and ferroelectric polarization. Au/BFO/Pt structure exhibited improved ferroelectric properties with enhanced saturation polarization of Ps = 33.53 μC/Cm2 along with remnant polarization of Pr = 19.34 μC/Cm2 as compared to other structures. The open circuit voltage and short circuit photocurrent density were found to be −1.09 V and 11.73 mA/cm2 respectively. The elevated ferroelectric photovoltaic response obtained in current work may be accredited to the existing substantial depolarization field as a result of superior remnant polarization.