Atomic-Level Engineering of Silicon Carbide Nanotubes: Structural, Electronic, and Thermal Modulation via Boron and Nitrogen Doping

This study presents a comprehensive first-principles investigation into the structural, electronic, and thermal properties of pristine and doped silicon carbide nanotubes (SiCNTs), with a focus on boron and nitrogen substitution. Pristine SiCNTs exhibit characteristic Si?C bond lengths of 1.79 ? and near-planar bond angles, consistent with theoretical expectations. Doping introduces significant structural distortions, including altered bond lengths, narrowed bond angles, and increased torsional strain, which enhance steric effects and surface reactivity. Binding energy calculations confirm the thermodynamic stability of all doped configurations, with co-doping yielding the most energetically favorable structures. Electronic structure analysis reveals a substantial reduction in band gap from 2.029 eV in pristine SiCNTs to near-zero values in certain doped models driven by symmetry breaking, defect-induced states, and orbital hybridization. Density of states (DOS) analysis highlights the strong influence of dopant orbitals on the valence and conduction bands, enhancing charge carrier mobility and conductivity. Thermal analysis shows that doping significantly reduces phonon transport efficiency due to mass disorder and lattice distortions, with co-doping configurations exhibiting up to 70% reduction in thermal conductivity. These findings demonstrate the effectiveness of atomic-level doping in tuning the multifunctional properties of SiCNTs, positioning them as promising candidates for applications in nanoelectronics, optoelectronics, thermoelectric, and sensing technologies.