First-Principles Investigation of Substitutional Boron and Phosphorus Doping in Crystalline Silicon

In this work, a systematic first-principles study of substitutional doping in crystalline silicon by boron and phosphorus is presented using Density Functional Theory (DFT). Calculations were performed within the generalized gradient approximation employing the Perdew-Burke-Ernzerhof functional as implemented in the Quantum ESPRESSO [1] package. A large 4 × 4 × 2 supercell containing 256 atoms was used to simulate dilute doping conditions. Structural relaxation, electronic band structures, and densities of states were analyzed for pure and doped systems. In addition, ab initio molecular dynamics simulations at 300 K were carried out to assess thermal stability, and hybrid HSE06 [2] [3] calculations were employed to correct the electronic band gap. The results reveal that boron introduces shallow acceptor states near the valence band, while phosphorus generates shallow donor states close to the conduction band, with only minor perturbations of the global band structure. Hybrid functional corrections significantly improve the band gap values, yielding results consistent with experimental data. These findings provide a reliable microscopic description of doped silicon and are relevant for microelectronic and photovoltaic applications.