Imaging of Microwave Permittivity, Tunability, and Damage Recovery in (Ba,Sr)TiO3 Thin Films

TL;DR

This paper presents a near-field microwave microscopy technique for high-resolution imaging of dielectric permittivity and tunability in (Ba,Sr)TiO3 thin films, revealing effects of annealing on damage recovery.

Contribution

It introduces a method for quantitative, micron-scale imaging of dielectric properties and tunability in thin films, including damage recovery analysis.

Findings

High-resolution permittivity images at 7.2 GHz

Detection of small permittivity changes as low as 2

Observation of dielectric tunability recovery after annealing

Abstract

We describe the use of a near-field scanning microwave microscope to quantitatively image the dielectric permittivity and tunability of thin-film dielectric samples on a length scale of 1 micron. We demonstrate this technique with permittivity images and local hysteresis loops of a 370 nm thick barium strontium titanate thin film at 7.2 GHz. We also observe the role of annealing in the recovery of dielectric tunability in a damaged region of the thin film. We can measure changes in relative permittivity as small as 2 at 500, and changes in dielectric tunability as small as 0.03 V$^{-1}$.