The role of native defects and common impurities doping in <i>κ</i> -Ga2O3 from first principles

We present a systematic study of properties of native defects and common impurities (H, Si, and C) on the electrical properties of κ-Ga2O3 and find that oxygen vacancies are the most stable intrinsic defects in κ-Ga2O3 and act as deep donors, not providing n-type background carriers. Under the ideal condition of no mutual combination of background impurities (Ga-rich and low defect concentration), the isolated common impurities (H, Si, and C) in κ-Ga2O3 all behave as shallow donors. H impurities tend to exist in an interstitial form and have low migration barriers, making them easy to eliminate by annealing. However, due to the low formation energy of the C–H complex, H cannot be easily removed by annealing or other post-treatment methods when H and C impurities coexist. The C–H complex has deep-level characteristics, which can effectively passivate C shallow donor defects and compensate for acceptor defects, thus reducing the background carrier concentration. In contrast, the formation energy of the Si–H complex is higher, making it less likely to form, thus Si impurities remain effective shallow donors. Our work offers fundamental insights into κ-Ga2O3 for its technological applications.