Nanoscale Ferroelectric Switchable Polarization and Leakage Current Behavior in (Ba0.50Sr0.50)(Ti0.80Sn0.20)O3Thin Films Prepared Using Chemical Solution Deposition

Venkata Sreenivas Puli,Ram S Katiyar,Douglas B Chrisey,Shiva Adireddy,Dhiren K Pradhan

doi:10.1155/2015/340616

Abstract

Nanoscale switchable ferroelectric (Ba0.50Sr0.50)(Ti0.80Sn0.20)O3-BSTS polycrystalline thin films with a perovskite structure were prepared on Pt/TiOx/SiO2/Si substrate by chemical solution deposition. X-ray diffraction (XRD) spectra indicate that a cubic perovskite crystalline structure and Raman spectra revealed that a tetragonal perovskite crystalline structure is present in the thin films. Sr2+and Sn4+cosubstituted film exhibited the lowest leakage current density. Piezoresponse Force Microscopy (PFM) technique has been employed to acquire out-of-plane (OPP) piezoresponse images and local piezoelectric hysteresis loop in polycrystalline BSTS films. PFM phase and amplitude images reveal nanoscale ferroelectric switching behavior at room temperature. Square patterns with dark and bright contrasts were written by local poling and reversible nature of the piezoresponse behavior was established. Local piezoelectric butterfly amplitude and phase hysteresis loops display ferroelectric nature at nanoscale level. The significance of this paper is to present ferroelectric/piezoelectric nature in present BSTS films at nanoscale level and corroborating ferroelectric behavior by utilizing Raman spectroscopy. Thus, further optimizing physical and electrical properties, BSTS films might be useful for practical applications which include nonvolatile ferroelectric memories, data-storage media, piezoelectric actuators, and electric energy storage capacitors.

Highlights

Perovskite oxide materials are the most studied functional materials for ferroelectric, ferromagnetic, magnetoresistive, and memristive applications
The present study focuses on the ferroelectric switching behavior at nanoscale level by utilizing Piezoresponse Force Microscopy (PFM) studies along with other bulk properties including X-ray diffraction ∼XRD, Raman spectroscopy, and leakage current behavior of the BSTS films deposited on Pt/TiOx/SiO2/Si substrates by chemical solution deposition
The XRD patterns indicate that BSTS has a perovskite crystalline structure as shown in Figure 2, which is demonstrated by the Raman spectroscopic measurements

Summary

Introduction

Perovskite oxide materials are the most studied functional materials for ferroelectric, ferromagnetic, magnetoresistive, and memristive applications. By suitable site engineering (chemical doping/substitution) with either isovalent or aliovalent elements at Ba2+ or/and Ti4+ site in BaTiO3 (BTO) leads to changes in the structure with improved electrical properties, the magnitude of dielectric constant, ferroelectric to paraelectric phase transition temperature, and dielectric tunable properties in the wide range of temperature to meet the variety of device applications. Improved properties at nanoscale architecture are due to altered atomic configurations and increased surface area to volume ratio Both nanoscience and nanotechnology are interdisciplinary and have vast variety of applications in scientific, industrial, and biological fields. Temperature and electric field dependent dielectric properties, micro Raman, and ferroelectric polarization measurements on this film are in progress and will be reported elsewhere

Experimental Details

Results and Discussion

Conclusion