Improved Tunability and Energy Storage Density Properties of Low-Loss, Lead-Free (Ba0.50Sr0.50)TiO3 and Ba(Zr0.15Ti0.85)O3 Bilayer Thin Film Stacks

M L V Mahesh,V V Bhanu Prasad,A R James,Prem Pal

doi:10.1007/s11664-021-09329-1

Abstract

Multilayer thin films of (Ba0.50Sr0.50)TiO3 (BST) and Ba(Zr0.15Ti0.85)O3 (BZT) were designed and grown using pulsed laser deposition technology. The periodic (BST/BZT)n thin films were deposited on Pt‹111›/SiO2/Si substrates. X-ray diffraction revealed the presence of a polycrystalline, perovskite structure corresponding to the bilayer thin film stacks. Scanning electron microscopy confirmed the multilayer structure without any interdiffusion across layers. It was also found that the dielectric and ferroelectric properties of the thin films were strongly influenced by the periodic heterostructures. The thin film stacks exhibited significantly higher tunability as compared with multilayer thin films grown on various single-crystal substrates such as LaAlO3, MgO and SrTiO3. Possible mechanisms explaining the other observed attributes such as improved dielectric properties and reduced leakage current are discussed. The effect of incorporating a comparatively lower-permittivity thin film in the multilayer stacks is presented. The observed properties of such multilayer structured films will aid in realizing low-loss and highly tunable applications.

Highlights

IntroductionDielectric capacitors play an important role in the development of electric industry due to their high power density (up to 100W/kg), faster charge-discharge capabilities, longer life time, temperature stable electrical properties especially in advanced electronics and electrical power systems such as hybrid electric vehicles, high frequency inverters, and power grids [1,2]
Dielectric capacitors play an important role in the development of electric industry due to their high power density, faster charge-discharge capabilities, longer life time, temperature stable electrical properties especially in advanced electronics and electrical power systems such as hybrid electric vehicles, high frequency inverters, and power grids [1,2]
The phase purity crystalline nature confirmed from the measured intensities and the values of the fullwidth-half maximum (FWHM) of the diffraction peaks

Summary

Introduction

Dielectric capacitors play an important role in the development of electric industry due to their high power density (up to 100W/kg), faster charge-discharge capabilities, longer life time, temperature stable electrical properties especially in advanced electronics and electrical power systems such as hybrid electric vehicles, high frequency inverters, and power grids [1,2]. Researchers are trying to improve the energy storage density of dielectric capacitors coupled with minimum dielectric loss over the past decades. Tunable devices exhibit decrease in capacitance with increasing applied electric field and find numerous applications viz., tunable filters, phase shifters, voltage controlled oscillators. (Ba1-xSrx)TiO3 is an extensively studied material system for numerous high frequency applications [3]. Several studies were reported with domain engineering, doping, modification of stress and strain in the films, growing films of different Ba/Sr & (Ba+Sr)/Ti ratios to improve the film material properties [4]. Energy storage devices at different working temperatures can be fabricated using these materials owing to the material’s property to attain high dielectric constant at desired temperatures by controlling composition of the constituents. The relatively low breakdown strength as well as poor temperature stability near TC limits its application in dielectric capacitors [5]

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Results

Conclusion