Exploring the Structural and Electronic Properties of Different Types of Silicon Nanotubes: A First-Principles Study

The exploration of silicon nanotubes (SiNTs) has garnered significant interest in recent years due to their potential applications in various fields, including microelectronics, nano-optics, and energy-storage devices. Unlike carbon nanotubes, SiNTs exhibit unique structural and electronic properties owing to the distinctive bonding characteristics of silicon atoms. While theoretical investigations have provided valuable insights into the stability and electronic properties of SiNTs, experimental synthesis methods have faced challenges in producing single-walled SiNTs with diameters comparable to their carbon counterparts. This study employed theoretical methods to investigate the structural stability, bonding properties, and electronic structure of different types of SiNTs. Our analysis covers a range of SiNT geometries, including armchair and zigzag hexagonal (h-SiNTs) and gear-like (g-SiNTs) as well as ladder-like (l-SiNTs) structures with different diameters. The h- and g-SiNTs show higher stability at larger diameters, while the l-SiNTs are more stable at lower diameters; surprisingly, the nanotube with pentagon cross-section shows the highest stability. Moreover, g-SiNTs generally show better stability than h-SiNTs. Additionally, electronic structure analyses reveal distinct structural and electrical properties of different SiNT types, providing valuable insights for future research and development in nanoelectronics and other applications. Except armchair g-SiNTs, almost all other SiNTs have a zero band gap.