First-principle crystal orbital insights to the unusual increase of carrier mobility in zigzag carbon nanotubes induced by Stone-Wales defects

Charge carrier mobility is a central transport property in nanoscale electronics. Due to the high carrier mobility, carbon nanotubes (CNTs) are good candidates for next-generation electronics. The preparation methods of CNTs have been greatly improved; however various kinds of defects always exist. It is commonly supposed that defect that exists unavoidably in the obtained nanomaterials, would block the movement of charge carriers, leading to a decreased mobility. However, theoretical predictions based on the first-principle calculations in this work reveal that the carrier mobilities of zigzag CNTs with Stone-Wales defects can be unexpectedly higher than those of pristine tubes. This interesting result is understood and explained with the aid of crystal orbital analysis. It is found that the unusual increase in carrier mobility of defective (11, 0) tube can be ascribed to the decreased deformation potential constants determined by the weaker acoustic scattering of the carriers. Besides, the size effects of CNTs on the carrier mobility induced by SW defects are also studied in this work. The mobility of CNTs induced by SW defects exhibit a 3-fold periodic pattern for zigzag CNT (n, 0) with n = 9-17.