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

• Published in: Journal of alloys and compounds 2021-10, Vol.877, p.160227, Article 160227
• Main Authors: Zeman, Charles J., Kielar, Samuel M., Jones, Leighton O., Mosquera, Martín A., Schatz, George C.
• Format: Article
• Language: English
• Subjects: Atomic properties; Defect engineering; Density functional theory; DFT; Electronic structure; Energy of formation; Free energy; Ga2O3; Gallium oxides; Heat of formation; Hydrogen; p-Type; P-type semiconductors; Semiconductor; Silicon
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160227

We have systematically investigated the effects of all possible combinations of vacancies and silicon substitutions on the electronic structure of the β and κ 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 κ 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