Electronic and structural properties of carbon nanotubes modulated by external strain

Abstract

Responses of work functions to uniaxial strain on infinite-length single-walled armchair (AC) [(2, 2) and (7, 7)] and zigzag (ZZ) [(3, 0) and (12, 0)] carbon nanotubes (CNTs) are investigated based on density functional theory. It is found that as strain increases, the work function of ZZ (3, 0) tubes decreases monotonically from 6.2 to 5.7 eV, whereas that of AC (2, 2) tubes varies between 4.6 and 5.3 eV in a somewhat complicated manner. For ZZ (12, 0) and AC (7, 7) tubes with large diameters, the work function of ZZ (12, 0) changes almost linearly from 4.2 to 4.8 eV, while for AC (7, 7) work function values grow monotonically from 4.1 to 4.7 eV. The energy band changes provide a qualitative understanding of how work function is affected by the uniaxial strain. Our findings are helpful not only for understanding the electronic properties of strained CNTs but also open the possibility of potential applications in CNT-based electronics devices.