Effects of the central armchair nanotube size on the conductance of carbon nanotube quantum dots

Abstract

Recently, one of the most significant topics in electronic devices is miniaturization. It has been a growing interest in some mesoscopic systems such as quantum dots. The size of these quantum dots approaches to the atomic scale, which contributes to interesting new behaviors. Understanding their properties is an important problem in the fields of nano electronics. Here we study the transport properties of the single wall carbon nanotubes quantum dots. Considering Carbon nanotube (2n,0)/1(n,n)/m(2n,0) quantum dot, we have investigated the effects of the central cell size on the conductance of the system. By increasing the length of armchair carbon nanotube in metalmetal- metal quantum dot m(12,0)/1(6,6)/m(12,0) , we have observed reduction in the conductance. In semiconductor- metal- semiconductor quantum dots (8,0)/1(4,4)/m(8,0), increasing the length of armchair part causes the scattering rate raising. For more than special length, due to the destructive and constructive interference of the wave functions, the conductance gap oscillates near the Fermi energy. Therefore, by controlling on cell size characteristics, it is possible to manipulate some efficient devices in nano-electronics.