Enhanced microwave dielectric tunability of Ba0.5Sr0.5TiO3 thin films grown with reduced strain on DyScO3 substrates by three-step technique

Authors

Hongrui Liu, Virginia Commonwealth University
Vitaliy Avrutin, Virginia Commonwealth UniversityFollow
Congyong Zhu, Virginia Commonwealth University
Ümit Özgür, Virginia Commonwealth UniversityFollow
Juan Yang, Beijing University of Technology
Changzhi Lu, Beijing University of Technology
Hadis Morkoç, Virginia Commonwealth UniversityFollow

Document Type

Article

Original Publication Date

2013

Journal/Book/Conference Title

Journal of Applied Physics

Volume

113

Issue

4

DOI of Original Publication

10.1063/1.4789008

Comments

Originally published at http://dx.doi.org/10.1063/1.4789008

Date of Submission

October 2015

Abstract

Tunable dielectric properties of epitaxial ferroelectric Ba_0.5Sr_0.5TiO₃ (BST) thin films deposited on nearly lattice-matched DyScO₃ substrates by radio frequency magnetron sputtering have been investigated at microwave frequencies and correlated with residual compressive strain. To reduce the residual strain of the BST films caused by substrate clamping and improve their microwave properties, a three-step deposition method was devised and employed. A high-temperature deposition at 1068 K of the nucleation layer was followed by a relatively low-temperature deposition (varied in the range of 673–873 K) of the BST interlayer and a high-temperature deposition at 1068 K of the top layer. Upon post-growth thermal treatment at 1298 K the films grown by the three-step method with the optimized interlayer deposition temperature of 873 K exhibited lower compressive strain compared to the control layer (−0.002 vs. −0.006). At 10 GHz, a high dielectric tunability of 47.9% at an applied electric field of 60 kV/cm was achieved for the optimized films. A large differential phase shift of 145°/cm and a figure of merit of 23°/dB were obtained using a simple coplanar waveguide phase shifter at 10 GHz. The low residual strain and improved dielectric properties of the films fabricated using the three-step deposition technique were attributed to reduced clamping of the BST films by the nearly lattice-matched substrate.

Rights

Liu, H., Avrutin, V., & Zhu, C., et al. Enhanced microwave dielectric tunability of Ba0.5Sr0.5TiO3 thin films grown with reduced strain on DyScO3 substrates by three-step technique. Journal of Applied Physics, 113, 044108 (2013). Copyright © 2013 American Institute of Physics.

Is Part Of

VCU Electrical and Computer Engineering Publications