Strain- and chirality-engineered tunability of electronic and thermoelectric properties in SiC nanotubes: insights from first-principles calculations.

Silicon carbide nanotubes (SiCNTs) have recently emerged as promising candidates for next-generation thermoelectric applications, owing to their moderate bandgaps and intrinsically lower lattice thermal conductivity-attributable to strong quantum confinement effects. In realistic situations, uniaxial strain arising from lattice mismatch, thermal gradients, or dynamic motion in wearables can significantly modulate the electronic and thermoelectric performance of these nanostructures. In this work, we systematically investigate the strain-dependent electronic and thermoelectric properties of four representative single-walled SiCNTs-three zigzag [(6,0), (10,0), and (11,0)] and one armchair [(6,6)]-using first-principles calculations coupled with Boltzmann transport theory. The results reveal distinct chirality-dependent responses to both compressive and tensile strains. The (6,6) armchair SiCNT exhibits an indirect bandgap of 2.63 eV, while all zigzag SiCNTs show direct bandgaps under strain, with (6,0) showing the narrowest gap (0.49 eV). The Seebeck coefficient remains stable (∼1550 µV K