Reducing deformation of single-walled defective silicon carbide nanotubes under charge injection: a first principles study

Silicon carbide (SiC) based one-dimensional nanotubes possess distinctive physicochemical properties, make them attractive for semiconductor applications. In this context, defective SiC nanotube (D-SiCNTs), in particular, offer enhanced structural and electronic tunability due to their defect-driven characteristics. The formation of D-SiCNTs involves a complex interplay between electrostatic forces and edge-to-edge covalent interactions originating from AA-stacked bilayer zigzag SiC nanoribbons. By using first principles calculations, we investigated the structural stability and electronic properties of both undeformed and radially deformed D-SiCNTs. The results indicate that undeformed D-SiCNTs are structurally stable and exhibit semi-metallic behavior, where the energy bands near the Fermi level are predominantly arisen from Si-Si as well as C-C dimers. For larger diameter nanotubes (<i>n</i> ≥ 10), radial deformation occurs due to insufficient strain energy. Applied charge injection significantly modifies the structural and electronic properties of these nanotubes. Hole injection causes an expansion of the nanotube, increasing the Si-Si bond up to 10.6%, while electron injection causes a contraction of the structure, as well as converting the nanotube from being semi-metallic into metallic. Remarkably, the calculated bond strain values surpassed those typically found in conventional materials, highlighting the unique electromechanical response of D-SiCNTs. Nudged elastic band calculations indicate that an externally applied force facilitates the splitting of the charge-injected (10,10) D-SiCNT into stable (5,5) D-SiCNT subunits. This finding reveals a controllable pathway for nanotube synthesis, which can be utilized in nanoscale device applications. Overall, the D-SiCNTs exhibit significant potential for tunable nanodevices, electromechanical actuators, and advanced nanoelectronic applications.