Realizing giant ferroelectricity in stable wz-Al1−xBxN alloys by controlling the microstructure and elastic constant

Abstract

The emerged wurtzite (wz) Al_1−xB_xN alloy has drawn increasing attention due to its superior ferroelectricity and excellent compatibility with microelectronics. We find that the stability and ferroelectric switching pathways of wz-Al_1−xB_xN alloys are affected by the orbital contribution, covalent bond strength, and elastic constant C₁₄. As the concentration of B increases, the internal parameter u decreases while the elastic constant C₁₄ increases, leading to an increase in spontaneous polarization and a decrease in the polarization switching barrier. The spontaneous polarization, polarization switching barrier, and band gap of wz-Al_1−xB_xN alloy can be further improved through the application of strain in a specific direction, resulting in a giant ferroelectricity. Additionally, the phase transformation of the wz-Al_1−xB_xN alloy induced by the increasing B composition can be regarded as a sequential process involving shrinkage, rotation, and deformation of tetrahedron. These findings give a deep understanding of the ferroelectric wz-Al_1−xB_xN alloy, and provide a guideline for designing a high-performance ferroelectric wz-Al_1−xB_xN alloy.