Electronic structure and defect chemistry of N-doped κ -Ga 2 O 3 : challenges toward P-type doping

Abstract Ga 2 O 3 has garnered substantial interest owing to its promising applications in power electronics and optoelectronics. Herein, the electronic properties of N-doped κ -Ga 2 O 3 are explored through density functional theory calculations. A variety of N-doped complex defects are examined, including N O (N-doped κ -Ga 2 O 3 ), N O V O (N-doped κ -Ga 2 O 3 with O vacancy), N O V Ga (N-doped κ -Ga 2 O 3 with Ga vacancy), N O O i (N-doped κ -Ga 2 O 3 with O interstitial), N O Ga i (N-doped κ -Ga 2 O 3 with Ga interstitial), alongside nitrogen substituting gallium at tetrahedral ( N Ga , tetra ) and octahedral ( N Ga , octa ) sites. Analysis of their formation energies reveals that N O predominates under both Ga-rich and O-rich environments, functioning as a shallow acceptor. Intriguingly, under Ga-rich conditions, there exists a pronounced preference for N O V O defects over other acceptor-like deep defects, implying that such complexes may obstruct the attainment of p-type conductivity in κ -Ga 2 O 3 due to extensive compensation by oxygen vacancies. Moreover, it is demonstrated that N O V O complexes can elicit red luminescence, arising from oxygen vacancies coupled with holes localized at acceptor sites introduced by N doping. The intricate electronic structure of κ -Ga 2 O 3 with these complex defects is elucidated through comprehensive analyses of the density of states and electronic band structures. Complementary examinations of electron localization and real-space wavefunctions further illuminate the influence of these defects on the κ -Ga 2 O