Spin modulates the electronic and magnetic properties of germanium-doped silicon with vacancies and charge states by first-principles calculation

Abstract

Silicon (Si) is the dominant material in the semiconductor industry with some novel properties, the introduction of germanium (Ge) and vacancies lead to special electronic and magnetic properties. In this work, the effects of spin-polarized electrons regulate the electronic and magnetic properties for substituted Ge in bulk crystalline Si (GeSi) with vacancies and electrical charge states introduced are investigated based on first-principles calculations. It is found that the electron spin density of Ge-vacancy (GeV) and Ge-divacancy (GeV2) complex structures is redistributed, the number of the defect energy levels is changed, and the magnetic moment on atoms appears when vacancies are introduced in GeSi. In addition, the distribution of the defect energy levels in the band gap is affected by charge states (negative and neutral), resulting in changes in the degree of spin-splitting, orbital occupation and electron filling, energy levels degeneracy, and the magnitude of the magnetic moment. These results show that the spin polarization on GeSi with vacancies and charge states, the number and the distribution of the vacancies around Ge, all play important roles in regulating the magnetic moments, magnetic properties, and the magnitude and distribution of defect energy levels.