Paper MN-TuP2
Understanding the Influence of Space Charge Region on Electrical Behavior of ( Pb_0.95La_0.05)(Zr_0.54Ti_0.46)O₃ Thin Film Capacitors Designed using Top Electrodes of Different Various Work Functions

Tuesday, October 31, 2017, 6:30 pm, Room Central Hall

Ferroelectric lanthanum modified lead zirconate titanate (PLZT) material has excellent electronic and optical properties due to which it meets the requirements for various device applications such as optical modulators/transducers, MEMS and smart sensors. Recently this material is being explored for photovoltaic applications. To design devices, the material is integrated with conducting electrodes to prepare metal/ferroelectric/metal (MFM) heterostructures. Electrical behavior of the devices strongly depend on the properties of the electrode/s used to design the MFM structures. In this work, we investigated the dependence of electrical properties of metal/PLZT/Pt capacitors, on a variety of top electrodes, having different work functions (Au, Pt etc.) with Pt serving as bottom electrode.

Thin films of Pb_0.95La_0.05Zr_0.54Ti_0.46O₃ (PLZT) were fabricated on Pt(111)/Ti/SiO₂/Si(100) substrates by chemical solution deposition method. Various metal electrodes, with varying work functions, were deposited on top of these films to prepare metal/PLZT/Pt capacitors. The prepared MFM heterostructures form space charge regions at the interfaces between PLZT film and electrode material. Due to different top electrode used to design the capacitor structure, the top interface differs from each other. A detailed analysis of the polarization-electric field (P-E) curves, capacitance-voltage (C-V) characteristics, permittivity-frequency (Ɛ_r-f), and current-voltage (I-V) measurements of each of the capacitors allowed us to understand the variation in electrical properties as a function of top electrodes. This variation is mainly attributed to the modification in metal/ferroelectric Schottky contact at the top interfaces which results in creation of different interface electric field, thus altering the properties of PLZT thin film capacitors. Results obtained from this study can guide us to choose the correct electrode material for designing capacitors for a particular application (photovoltaic devices or other types of sensors).