Ferroelectricity of wurtzite Be1−xMgxO from first-principles calculation

Abstract

Nitride ferroelectrics such as Al1−xScxN are emerging as promising ferroelectrics for nonvolatile memory technologies due to their high thermal stability and large remnant polarization. However, their high coercive field close to the breakdown limit causes high leakage current, which limits their device applications. Here, we use first-principles calculations to investigate wurtzite Be1−xMgxO as a promising oxide-based ferroelectric alternative. We show that Be1−xMgxO alloys maintain structural stability in the wurtzite phase up to x = 0.83 and exhibit an ultrawide bandgap over 6.2 eV across all compositions, which provides high intrinsic breakdown fields (12–71 MV/cm). The polarization switching barrier decreases significantly with increasing Mg while the coercive field remains well below the intrinsic dielectric breakdown field. Our findings predict that wurtzite Be1−xMgxO is an alternative ferroelectric oxide that has the potential to offer low leakage current and a widely tunable range of polarization and switching characteristics while preserving high dielectric strength.