Investigation of p-type doping in β- and κ-Ga2O3

We have systematically investigated the effects of all possible combinations of vacancies and silicon substitutions on the electronic structure of the beta and kappa phases of Ga2O3 using plane-wave density functional theory (DFT) methods. It was found that VGa defects are associated with a sufficient shift of the Fermi level to lower energy to induce p-type behavior, with formation energies in the range of 9.0 +/- 0.2 eV. Calculations with single atom substitutions in the kappa phase, including nitrogen, phosphorous, and silicon, did not show p-type character, although NO substitutions may lead to shallow acceptor states. In the pursuit of elucidating how MOCVD growth of Ga2O3 can result in p-type behavior, as indicated by experimental results in the literature, we examined the role of combining hydrogen and silicon substitutions. The results showed that p-type behavior is observable when gallium atoms are substituted for hydrogen within the coordination sphere of SiO substitutions. This shows that silicon can act as an amphoteric dopant for p-type Ga2O3 semiconducting materials when hydrogen is included with formation energies < 6.0 eV. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study systematically investigated the effects of vacancies and silicon substitutions on the electronic structure of Ga2O3, and found that silicon can act as an amphoteric dopant for p-type behavior under certain conditions.