Tailoring the electronic properties of silicon nanotubes: unraveling the impact of perpendicular electric fields

Abstract This study investigates the influence of a perpendicular electric field ( E ⊥ ) on the electronic properties of silicon nanotubes (SiNTs) using first-principles calculations. The application of E ⊥ induces significant changes in the band structure, including a systematic reduction in the band gap ( E g ) and the onset of a semiconductor-to-metal transition at a critical field strength ( E ⊥, c ). These alterations stem from charge redistribution, which modifies electronic confinement and enhances the density of free carriers. Additionally, E ⊥ disrupts subband degeneracy, increases subband spacings, and introduces pronounced subband anticrossings and oscillatory behaviors. These phenomena arise from anisotropic charge redistribution and the complex interplay between the applied field, the hexagonal symmetry of SiNTs, and their structural buckling. An in-depth analysis of spatial charge density distribution and projected density of states (PDOS) elucidates these phenomena. This work not only unravels the physical mechanisms underlying the electric field effect but also demonstrates the potential of E ⊥ as a precise and powerful tool for tailoring the electronic properties of SiNTs, facilitating their use in next-generation nanoelectronic and optoelectronic devices.