Exploring the effective P-type dopants in two-dimensional Ga2O3 by first-principles calculations

Exploring effective p-type doping in Ga2O3 is crucial for both fundamental science and emerging applications. Recently, N and Zn elements have been shown to exhibit considerable contributions to effective p-type doping in 3D Ga2O3 experimentally and theoretically, whereas the studies of their doping behaviors in 2D Ga2O3 are rare. In this study, we investigate the possibilities of N and Zn elements to achieve effective p-type doping, manifesting in the introduction of shallow acceptor levels typically less than 0.5 eV in 2D Ga2O3 using first-principles calculations with the generalized gradient approximation + U method. The calculated defect formation energies suggest that the N-doped 2D Ga2O3 structures are more easily formed under Ga-rich conditions, while the Zn-doped structures are more readily generated under O-rich conditions. Moreover, the introduced N and Zn atoms preferentially incorporate on the threefold coordinated OII and pyramidally coordinated GaI sites, accompanying with N3− and Zn2+ oxidation states in 2D Ga2O3, respectively. In particular, the electronic structures indicate that the occupied N-2p and semi-occupied Zn-3d orbitals produce shallow hole levels ranging from 0.09 to 0.33 eV, demonstrating that N and Zn atoms can behave as effective p-type dopants in 2D Ga2O3. The magnetic moments for N- and Zn-doped 2D Ga2O3 are 1.00 μB due to the doping of one hole, where the magnetic moments can be mainly attributed to the N atom and the nearest O atoms, respectively. Our work may offer theoretical guidance for the design of p-type 2D Ga2O3 materials and shed light on its potential optoelectronic and magnetic applications.