I–V characteristics and conductance of strained SWCNTs

Abstract

We present a new procedure to investigate the I–V characteristics and the conductance for strained SWCNTs. These electronic transport properties have been studied theoretically at zero temperature for zig-zag, armchair and chiral SWCNTs under the effect of the uniaxial tension and torsional strain. The analytical expression of the energy spectrum in the tight binding approximation has been used to calculate the induced current and the conductance through Landauer–Büttiker formalism. It is shown that the conductance for unstrained CNTs at initial values of the voltage can take discrete values which are equal to zero and 4 (e2/h) for semiconducting and conducting SWCNTs respectively. The emergence of the kinks in the I–V characteristics is due to the discrete electronic spectrum in the SWCNTs. The location and number of kinks are changeable under the effect of strain process. The conductance in a strained armchair (5,5) CNT decreases to zero under torsional strain, consequently, it will transform the conducting SWCNTs at a threshold value of strain to a semiconducting SWCNT. In contrast, by applying the uniaxial tension on the armchair (5,5) CNT, the conductance does not change absolutely. There is a different behavior can be observed by applying the strain on zig-zag (10,0) CNT, where the conductance decreases rapidly and slightly under the influence of uniaxial tension and torsional strain, respectively. We found that the conductance of chiral (10,9) CNT is not significantly affected by applying the strain under consideration. More interestingly, the band structure of chiral (10,9) CNT under uniaxial tension and torsional strain have been investigated within the tight binding approximation.