Lee Cheng-Wei, Yazawa Keisuke, Zakutayev Andriy, Brennecka Geoff L, Gorai Prashun
Colorado School of Mines, Golden, CO 80401, USA.
National Renewable Energy Laboratory, Golden, CO 80401, USA.
Sci Adv. 2024 May 17;10(20):eadl0848. doi: 10.1126/sciadv.adl0848.
Wurtzite-type ferroelectrics have drawn increasing attention due to the promise of better performance and integration than traditional oxide ferroelectrics with semiconductors such as Si, SiC, and III-V compounds. However, wurtzite-type ferroelectrics generally require enormous electric fields, approaching breakdown, to reverse their polarization. The underlying switching mechanism(s), especially for multinary compounds and alloys, remains elusive. Here, we examine the switching behaviors in AlScN alloys and wurtzite-type multinary candidate compounds we recently computationally identified. We find that switching in these tetrahedrally coordinated materials proceeds via a variety of nonpolar intermediate structures and that switching barriers are dominated by the more-electronegative cations. For AlScN alloys, we find that the switching pathway changes from a collective mechanism to a lower-barrier mechanism enabled by inversion of individual tetrahedra with increased Sc composition. Our findings provide insights for future engineering and realization of wurtzite-type materials and open a door to understanding domain motion.
纤锌矿型铁电体因其与硅、碳化硅和III-V族化合物等半导体相比，有望展现出比传统氧化物铁电体更好的性能和集成性，从而受到越来越多的关注。然而，纤锌矿型铁电体通常需要接近击穿的巨大电场来反转其极化。其潜在的开关机制，特别是对于多元化合物和合金而言，仍然难以捉摸。在此，我们研究了最近通过计算识别出的AlScN合金和纤锌矿型多元候选化合物中的开关行为。我们发现，这些四面体配位材料中的开关过程通过多种非极性中间结构进行，并且开关势垒由电负性更强的阳离子主导。对于AlScN合金，我们发现随着Sc成分的增加，开关途径从集体机制转变为由单个四面体反转实现的低势垒机制。我们的研究结果为纤锌矿型材料的未来工程和实现提供了见解，并为理解畴运动打开了一扇门。
