Synthesis of ferroelectric LaWN3 -- the first nitride perovskite

TL;DR

This paper reports the first successful synthesis and experimental confirmation of a nitride perovskite, LaWN3, exhibiting ferroelectric and piezoelectric properties, opening avenues for nitride-based electronic devices.

Contribution

It is the first experimental realization of a stable nitride perovskite with ferroelectric behavior, previously only predicted computationally.

Findings

LaWN3 thin films confirmed as polar perovskite structure

Large piezoelectric response observed in LaWN3

Strong evidence of ferroelectric behavior in LaWN3

Abstract

Next generation telecommunication technologies would benefit from strong piezoelectric and ferroelectric response in materials that are compatible with nitride radio-frequency electronic devices. Ferroelectric oxides with perovskite structure have been used in sensors and actuators for half a century, and halide perovskites transformed photovoltaics research in the past decade, but neither of them is compatible with nitride semiconductors. Nitride perovskites, despite numerous computational predictions, have not been experimentally demonstrated and their properties remain unknown. Here we report the experimental realization of the first nitride perovskite: lanthanum tungsten nitride (LaWN3). Oxygen-free LaWN3 thin films in a polar perovskite structure are confirmed by spectroscopy, scattering, and microscopy techniques. Scanning probe measurements confirm a large piezoelectric response and strongly suggest ferroelectric behavior, making it the first stable nitride ferroelectric compound. These results should lead to integration of LaWN3 with nitride semiconductors for wireless telecommunication applications, while enabling synthesis of many other predicted nitride perovskites.