Characterization of metalorganic decomposition-derived SrBi2Ta2O9 thin films with different thicknesses

Abstract

Properties of SrBi 2 Ta 2 O 9 ferroelectric thin films prepared by a modified metalorganic solution deposition technique Appl.Ferroelectric capacitors having sputtered Pt bottom and top electrodes and metalorganic decomposition derived ferroelectric thin films of SrBi 2 Ta 2 O 9 ͑SBT͒ were prepared. The thickness effects on the structure, surface morphology, and electrical properties of SBT thin films were studied and discussed. Structure and surface morphology were analyzed by x-ray diffraction and atomic force microscope. The electrical properties were characterized by the measurements of hysteresis, capacitance, and pulse switching. The crystalline structure, grain size, and electrical properties do not depend on film thickness when films are less than 440 nm thick. A larger grain size is observed for films thicker than 440 nm, which results in a larger remnant polarization. The thickness dependence of the coercive voltage and reciprocal capacitance can be explained by an interfacial layer model. The thickness-independent coercive field and dielectric constant, calculated from the interfacial layer model, are around 19 kV/cm and 343, respectively. Nonvolatile polarization ( P nv ), obtained from pulse-switching measurements, increases with the applied electric field and finally saturates with a slight thickness effect. The relaxation of the remnant polarization that occurs at zero-voltage intervals between the pulses and the thickness-independent behavior of P nv are explained based on depolarization fields within the ferroelectric due to nonswitching interfacial layers at the film/electrode interfaces.

Ferroelectric properties of (Bi3.15 Nd 0.85 )Ti 3 O 12 with decreasing film thickness

“…In particular, the film of 240 nm thickness exhibits a considerable higher 2Pr of ∼24 μC/cm 2 and a coercive field of 151 kV/cm, as comparable to the randomly orientated BNdT film prepared by other methods [8,9]. A similar polarization loop is shown for the film of 160 nm thickness, although there is a slight increase in coercive filed, which is related to the blocking layer that has been commonly observed in ferroelectric films [11,13]. In comparison, there is an obvious change in polarization loop for the BNdT of 120 nm in thickness, where a much slimmer P-E hystereis loop is observed.…”

“…To understand the ferroelectric thin films towards the nanometer scale, there has been attempt to refine the film thickness, which indeed has led to several unique phenomena in their ferroelectric behaviors [11][12][13]. Realization of improved electrical properties at reduced film thickness is of considerable interest, as the thin film and device technologies are driving towards miniaturization, for example for small cell size and low operating polarization voltage of FRAM (at 3 V or 5 V) [14].…”

Epitaxially grown ferroelectric thin films for agile devices

“…Several methods have been employed for the synthesis of thin films of SBN and, in a larger extent, its parent compound SrBi 2 Ta 2 O 9 (SBT), such as sol-gel [65][66][67], Metal-Organic Solution Deposition [68][69][70], metal-organic chemical vapor deposition (MOCVD) [71], polymeric precursors (Pechini process) [72], r.f. sputtering [73][74][75] and pulsed laser deposition (PLD) [61][62][63][76][77][78][79][80][81][82][83], including plasma-assisted PLD [84].…”

Nucleation and grain growth of SrBi2Nb2O9 thin films

“…Accordingly, the grain size is able to be large without a surface-roughening problem. It is reported that large grain size is favorable for enhancing electrical properties [21]. These microstructure characteristics such as a smooth surface morphology and a large grain size are superior properties to those of the elliptical grain growth.…”