Physics of Ferroelectric Wurtzite Al1−xScxN Thin Films

• Published in: Advanced electronic materials Vol. 11; no. 2
• Main Author: Yang, Feng
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01.02.2025
• Subjects: Al1−xScxN; ferroelectric memory; III‐nitride semiconductor; thin film; wurtzite ferroelectric
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202400279

Al1−xScxN emerges as a revolutionary ferroelectric material within the III‐N family. It combines exceptional switchable polarization (80–165 µC cm−2), highly tunable coercive fields (1.5–6.5 MV cm−¹), and a wide bandgap (4.9–5.6 eV). Unlike conventional ferroelectrics, Al1−xScxN exhibits remarkable compatibility with both CMOS and III‐N technologies. It can be fabricated on plastic substrates at low temperatures, demonstrating excellent flexibility and biocompatibility. Remarkably, Al1−xScxN maintains superior performance in harsh environments due to its outstanding thermal stability (up to 1100 °C). These unique characteristics position Al1−xScxN as a highly promising candidate for a wide range of applications, including high‐performance memory, in‐memory computing, neuromorphic computing, and next‐generation wearable and implantable devices, particularly for operation in complex environments. Despite its potential, Al1−xScxN faces challenges such as high coercive fields, significant leakage currents, and limited polarization reversal cycle life. Addressing these challenges require a deeper understanding of the fundamental physics controlling Al1−xScxN films. This review explores the origins of Al1−xScxN's ferroelectricity and phase stability, delves into the fundamental theory of wurtzite ferroelectricity, investigates mechanisms for controlling spontaneous polarization and coercive fields, examines recent research progress in Al1−xScxN ferroelectric devices, and outlines future development directions for this exciting material. This review highlights Al1−xScxN as a groundbreaking wurtzite ferroelectric with exceptional properties, including large polarization, tunable coercive field, outstanding thermal stability, and compatibility with CMOS/III‐N technologies. It explores the origins of its ferroelectricity, phase stability, and control mechanisms, discusses challenges such as high operating voltages and leakage currents, and outlines future development directions, emphasizing its potential for advanced applications.