First-principles properties of an intermediate band material based on Ti-implanted silicon

Abstract

A first-principles study is aimed to reveal the properties of a crystalline Ti-implanted Si compound obtained experimentally with a Ti concentration clearly above the corresponding equilibrium solubility limit and high enough to be capable of presenting an electronic intermediate band brought about by Ti 3d electrons instead of the well-known impurity levels structure. Interstitial, substitutional and other Ti implantation processes are considered, as well as several possible mixtures of them, in order to clarify the origin of a donor-kind transition observed experimentally at about 0.36 eV. Also the possibility of obtaining an intermediate band from the studied compound is considered. When convenient, calculations of magnetic and optical properties were carried out to help to identify this potential intermediate band material.