Exploring the Thermodynamic and Electronic Properties of Domain Walls in Wurtzite Ferroelectric ScGaN

III-nitrides such as AlN and GaN have high carrier mobilities and light-emitting efficiency that have enabled wide applications in semiconductor devices. Furthermore, the discovery of ferroelectricity in nitride materials has expanded the range of potential technological applications. In this work, we provide an atomic-scale understanding of the switching mechanisms and domain energetics that is critical to integrating ferroelectric wurtzites into devices. Using Density Functional Theory (DFT), we have uncovered the atomic configurations of domain walls observed experimentally in ScGaN, a representative ferroelectric nitride. We are able to confirm the presence of vertical (charge-neutral) and horizontal (charged) domain walls both in experiment and theory by comparing the atomic distances of their respective configurations. In addition, we find that the atomic configurations at charged domain walls enable a high charge density at the interface due to the presence of dangling bonds, which fully compensate the large polarization discontinuity and stabilize these interfaces without the formation of defects. Through the formation of midgap states in the electronic structure of the horizontal domain walls, we are able to confirm the electrically-active nature of these dangling bonds. Our findings provide insights into the switching mechanism of III-nitrides, and lay the groundwork for optimized device designs in the development of electronic materials.