Dielectric properties of strained NiO thin films

TL;DR

This study investigates how strain influences the dielectric properties of NiO thin films across a temperature range, revealing that strain enhances dielectric permittivity at low temperatures, especially in defective films.

Contribution

It provides new insights into the strain-dependent dielectric behavior of NiO thin films and links it to lattice dynamics, which was not previously well understood.

Findings

Strain increases dielectric permittivity below 100 K.

Defective films show higher dielectric constants at room temperature.

Atomically-ordered films exhibit stable dielectric properties across temperatures.

Abstract

The dielectric properties of NiO thin films grown by pulsed laser deposition have been studied as a function of strain at temperature from 10 to 300 K. Above 150 K, the contribution of space-charge polarization to the dielectric permittivity of NiO films becomes dominant and the more defective films, which were grown at low temperatures show a drastical increase in the dielectric constant up to room temperature. While the atomically-ordered film, which was grown at high temperature doesn't show any considerable change in the dielectric constant in the range from 10 to 300 K. Below 100 K, the effect of strain on the dielectric constant becomes clear. An increase in dielectric permittivity is observed in the strained films while the relaxed film doesn't show any remarkable deviation from its bulk value. The low-temperature dielectric behavior of NiO thin film can be interpreted based on the effect of strain on the lattice dynamics of rocksalt binary oxides.