Uncovering the origin of ferroelectricity in wurtzite nitrides: A first-principles comparison of ScAlN, YAlN, and BAlN

ScAlN has attracted significant attention following the revelation of its exceptional ferroelectric properties. Recent studies have indicated that YAlN, BAlN, as well as binary AlN also fall within the category of ferroelectric wurtzite nitrides. Despite the potential integration of this class of ferroelectric into memory applications due to their substantial remnant polarization and CMOS compatibility, there is still a limited understanding of their switching mechanism. In this study, we explore the impact of dopant incorporation in AlN on its ferroelectric properties, by focusing on their thermodynamic stability, local bonding, and electronic properties. To achieve this, we have conducted density functional theory (DFT) calculations to determine the mixing enthalpy and local bond ionicity of ScAlN, YAlN, and BAlN across various compositions. Furthermore, we examined how the chemical composition of the dopant affects the electronic properties of these materials by analyzing their electronic band structures. Our investigation aims to shed light on the origins of ferroelectricity in wurtzite nitrides, and guide the synthesis of new ferroelectric alloys with superior properties.