Defect Chemistry and Doping of Ultrawide Band Gap (III)BO3 Compounds

New wide band gap semiconductors are needed to increase the power, voltage, and switching frequency limits of power electronic devices. A recent computational search identified a family of ultrawide band gap (4.8–7.8 eV) group-III orthoborates as promising materials for power electronics, assuming n-type doping could be attained. Here-in, we test this assumption by investigating the defect chemistry and dopability of rhombohedral calcite-structured AlBO3, GaBO3, and InBO3 using first-principles calculations. Of the three, we find InBO3 to have the most potential for n-type doping without significant compensation by native acceptor defects. Furthermore, Zr is predicted to readily substitute for In and behave as a shallow donor with maximal net donor concentrations exceeding 1 × 1018 cm–3 under growth conditions typical for this class of materials. We also demonstrate thin film growth of InBO3 and measure its absorption onset, which we find to be consistent with theory. Ultimately, our results confirm the promise of InBO3 as an n-type ultrawide band gap semiconductor and point to alloying with GaBO3 and AlBO3 for further optimization of band gap and electron concentration for high-power applications.