Intrinsic Ferroelectricity in ɛ‐Ga ₂ O ₃ : Experimental and Theoretical Insights

Abstract The wide‐bandgap ferroelectric semiconductor epsilon gallium oxide (ɛ‐Ga 2 O 3 ) combines exceptional breakdown strength with electrically tunable polarization, enabling advancements in electronics, neuromorphic systems, and optoelectronic devices. Despite recent progress, investigation of ferroelectric behavior in ɛ‐Ga 2 O 3 remains at an early stage with various fundamental questions yet to be addressed. Herein, epitaxial growth of ɛ‐Ga 2 O 3 is achieved via mist chemical vapor deposition (CVD). Second‐harmonic generation (SHG) further reveals their non‐centrosymmetric nature and determines an elevated high Curie temperature of 690 K. The ɛ‐Ga 2 O 3 films display intercorrelated out‐of‐plane and in‐plane ferroelectricity. Theoretical calculations reveal that ferroelectricity originated from the displacement of Ga atoms along the c ‐axis. Leveraging this polarization behavior, a prototype ferroelectric nonvolatile device is developed, where a vertical ɛ‐Ga 2 O 3 memristor showed pronounced resistive switching with on/off ratio of 10 6 . The ɛ‐Ga 2 O 3 memristor‐based computing system, designed for intelligent automotive applications, demonstrates excellent multi‐target recognition capabilities. By deciphering the relationship between crystallographic symmetry and ferroelectric ordering in ɛ‐Ga 2 O 3 , this study would not only deliver experimental verification of its intrinsic ferroelectricity but also represent a pioneering exploration of novel applications based on its unique combination of ultrawide bandgap and ferroelectricity of Ga 2 O 3 .