Nanoscale Engineering of Wurtzite Ferroelectrics: Unveiling Phase Transition and Ferroelectric Switching in ScAlN Nanowires

TL;DR

This paper investigates phase transitions and ferroelectric switching in ScAlN nanowires, revealing tunable properties and potential for nanoscale device applications, advancing understanding of wurtzite ferroelectrics in reduced dimensions.

Contribution

It provides the first comprehensive study of phase transition and ferroelectric switching in ScAlN nanowires, demonstrating tunability and interface confinement effects.

Findings

Gradual phase transition from wurtzite to cubic with increasing Sc content

Confined wurtzite phase at the ScAlN/GaN interface for high Sc compositions

First evidence of ferroelectric switching in ScAlN nanowires

Abstract

The pursuit of extreme device miniaturization and the exploration of novel physical phenomena have spurred significant interest in crystallographic phase control and ferroelectric switching in reduced dimensions. Recently, wurtzite ferroelectrics have emerged as a new class of functional materials, offering intriguing piezoelectric and ferroelectric properties, CMOS compatibility, and seamless integration with mainstream semiconductor technology. However, the exploration of crystallographic phase and ferroelectric switching in reduced dimensions, especially in nanostructures, has remained a largely uncharted territory. In this study, we present the first comprehensive investigation into the crystallographic phase transition of ScAlN nanowires across the full Sc compositional range. While a gradual transition from wurtzite to cubic phase was observed with increasing Sc composition, we further demonstrated that a highly ordered wurtzite phase ScAlN could be confined at the ScAlN/GaN interface for Sc contents surpassing what is possible in conventional films, holding great potential to addressing the fundamental high coercive field of wurtzite ferroelectrics. In addition, we provide the first evidence of ferroelectric switching in ScAlN nanowires, a result that holds significant implications for future device miniaturization. Our demonstration of tunable ferroelectric ScAlN nanowires opens new possibilities for nanoscale, domain, alloy, strain, and quantum engineering of wurtzite ferroelectrics, representing a significant stride towards the development of next-generation, miniaturized devices based on wurtzite ferroelectrics.