Surface and morphological studies of LiNbO3: p-type semiconductivity on stoichiometric surfaces

Abstract

LiNbO₃ is a semiconductor material employed in the development of several technological devices and processes. However, its suitability is expanded when p-type semiconductivity is obtained. In this work, density functional theory (DFT) simulations using the B3LYP hybrid functional connect the surface and crystalline morphology of LiNbO₃ to its semiconductivity features. Thus, the main low-index surfaces were carefully investigated, presenting the influence of O vacancies on surface stability and structural and electronic features. The results also illustrate the electronic properties of surfaces in terms of band gap, charge carrier stability, and semiconductor type, the latter being dependent on the surface direction. Finally, a large set of possible crystalline morphologies for LiNbO₃ is presented, predicting the expected properties for different crystal shapes from the calculated surface properties. A particular behavior is found observing the existence of both p- and n-type semiconductivity in the same morphology.