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

The pursuit of extreme device miniaturization and the exploration of associated physical phenomena has spurred significant interest in crystallographic phase control and ferroelectric switching in reduced dimensions. The recently discovered wurtzite ferroelectrics offer intriguing piezoelectric and ferroelectric properties, CMOS compatibility, and seamless integration with mainstream semiconductor technology. In this study, we present a comprehensive investigation of 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 demonstrate that a highly ordered wurtzite phase ScAlN can be confined at the ScAlN/GaN interface for Sc contents surpassing what is possible in conventional films. 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 toward the development of next-generation, miniaturized devices based on wurtzite ferroelectrics.