Computational discovery of ultra-wide-band-gap semiconductors*

Our aim is to understand the factors that distinguish ultra-wide-band-gap (UWBG) semiconductors from insulators, and to discover new UWBG semiconducting materials that surpass the current state of the art. Despite decades of research, only a handful of UWBG semiconductors have been developed to date, and they all face challenges due to poor dopability and/or low conductivity. We apply predictive atomistic calculations in order to understand the fundamental limitations of current UWBG semiconductors such as Ga₂O₃ and AlGaN, and to discover new materials with improved functionality compared to the current state of the art. Our calculations uncovered the rutile polytype of GeO₂ as a promising UWBG semiconductor with shallow donors and relatively shallow acceptors, high carrier mobilities, and high thermal conductivity that can overcome the limitations of Ga₂O₃ in power electronics. Moreover, we have discovered several compounds with gaps wider than AlN (6.2 eV) that host shallow dopants and mobile carriers. Our analysis revealed that there is no upper band-gap limit that separates semiconductors from insulators and uncovers the rules to design new UWBG semiconductors with improved functional properties.