Cubic BeB₂: A metastable p-type conductive material from first principles

Boron forms a wide variety of compounds with alkaline earth elements because of its unique bonding characteristics. Among these, binary compounds of Be and B display particularly rich structural diversity, attributed to the small atomic size of Be. Cubic BeB₂ is a particularly interesting phase, in which Be donates electrons to stabilize a diamond-like boron network under high pressure. In this work, we employ ab initio methods to conduct a detailed investigation of cubic BeB₂ and its functional properties. We show that this metastable phase is dynamically stable under ambient conditions, and its lattice match to existing substrate materials suggests possible epitaxial stabilization via thin-film growth routes. Through a comprehensive characterization of its electronic, transport, and superconductivity properties, we demonstrate that cubic BeB₂ exhibits high hole concentrations and high hole mobility, making it a potential candidate for efficient p-type transport. In addition, cubic BeB₂ is found to exhibit low-temperature superconductivity at degenerate doping levels, similar to several other doped covalent semiconductors such as diamond, Si, and SiC.