First-principles analysis for electronic and optical properties of silicon doped with transition metals (Ti, V, Cr)

Abstract

Silicon, a material of significant value in the fields of optoelectronics and microelectronics, has experienced a marked increase in demand for its use in silicon photonics. Driven by the increasing demand, various materials, especially transition metals, have been doped into the silicon lattice to enhance its photon sensitivity and expand its infrared applications. In this study, the electronic and optical properties of three popular transition metals (Ti, V, Cr) doped silicon (M − Si) are systematically investigated using first-principles calculations. The atomic structures, formation energies, energy band structures, and spectral absorption characteristics of M − Si at various doping concentrations and occupied positions are examined. The results show that a substantial sub-bandgap absorption can be augmented by intermediate band (IB) assistant photon transition and hybridization of IB with CB or VB. The enhancement in sub-bandgap absorption is influenced by the variation of bandwidths and positions of the IB induced by different doping elements and occupations. The study further concluded that Ti is more suitable for silicon doping due to its combination of a deep-level impurity property, lowest formation energy, and the most significant sub-bandgap absorption. The present study provides both guidance and theoretical basis for the experimental fabrication of optimized transition metal-doped silicon materials.