# Room-temperature relaxor ferroelectricity and photovoltaic effects in SnTiOx/Si thin film heterostructures

## TL;DR

This study demonstrates room-temperature relaxor ferroelectricity and photovoltaic effects in SnTiOx/Si heterostructures, revealing their potential for green ferroelectric devices compatible with semiconductor processes.

## Contribution

It reports the first observation of room-temperature relaxor ferroelectricity and photovoltaic effects in SnTiOx thin films directly deposited on silicon, with experimental and theoretical analysis of their optical properties.

## Key findings

- Ferroelectric hysteresis with remnant polarization of 1.5 μC/cm² at room temperature.
- Photo-induced enhancement of ferroelectric polarization under white light.
- Ferroelectric photovoltaic behavior across visible to ultraviolet spectrum.

## Abstract

We have studied ferroelectricity and photovoltaic effects in atomic layer deposited (ALD) 40-nm thick SnTiO$_{x}$ films deposited directly onto p-type (001)Si substrate. These films showed well-saturated, square and repeatable hysteresis loops with remnant polarization of 1.5 $\mu$C/cm$^{2}$ at room temperature, as detected by out-of-plane polarization versus electric field (P-E) and field cycling measurements. A photo-induced enhancement in ferroelectricity was also observed as the spontaneous polarization increased under white-light illumination. The ferroelectricity exhibits relaxor characteristics with dielectric peak shifting from ca. T = 600 K at f = 1 MHz to ca. 500 K at 100 Hz. Moreover, our films showed ferroelectric photovoltaic behavior under the illumination of a wide spectrum of light, from visible to ultraviolet regions. A combination of experiment and theoretical calculation provided optical band gap of SnTiO$_{x}$ films which lies in the visible range of white light spectra. Our study leads a way to develop green ferroelectric SnTiO$_{x}$ thin films, which are compatible to semiconducting processes, and can be used for various ferroelectric and dielectric applications.

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Source: https://tomesphere.com/paper/1702.04791