Effective P-type N-doped α-Ga2O3 from First-Principles Calculations

The realization of an effective p-type doping in Ga₂O₃ is crucial for both fundamental science and emerging applications. P-type doping in the β-Ga₂O₃ phase has been observed tremendously, whereas the researches of p-type features in the allotropy α-Ga₂O₃ phase are rare. In this work, we study p-type N-doped α-Ga₂O₃ by first-principles calculations with generalized gradient approximation (GGA) + U method. The N foreigner can easily substitute the O atom in α-Ga₂O₃ and acts as an effective shallow hole dopant with a modest acceptor ionization level of ~ 0.1 eV. Moreover, the N³⁻, N²⁺, and N³⁻ are the predominant charge states, corresponding to one N impurity substitution of anion O, cation Ga, and the occupancy of the interstitial site in α-Ga₂O₃, respectively. N impurity leads to the optical transition from ultraviolet light to visible-infrared range in α-Ga₂O₃ as suggested by the dielectric function calculations, which can be ascribed to the transition from O 2p orbitals to N 2p orbitals or inter-band transition between the formed holes of N 2p impurity. Our work may provide theoretical guidance for designing p-type N-doped α-Ga₂O₃ materials and shed light on its application as potential optoelectronic devices.