arXiv subjects

S. S. Abukari

Publications and source records attributed to S. S. Abukari.

22 records · Page 2Linked to original sources

arXiv2011

Effect of laser on thermopower of chiral carbon nanotube

An investigation of laser stimulated thermopower in chiral CNT is presented. The thermopower of a chiral CNT is calculated using a tractable analytical approach. This is done by solving the Boltzmann kinetic equation with energy dispersion relation obtained in the tight binding approximation to determine the electrical and thermal properties of chiral carbon nanotubes. The differential thermoelectric power α along the circumferential and axial axes are obtained. The results obtained are numerically analyzed and α is found to oscillate in the presence of laser radiations. We have also noted that Laser source above 4.6 x 107V/m lowered the thermopower otherwise there is no change. Varying delta s and delta z the thermopower changes from positive to negative.

cond-mat.mes-hall↗

arXiv2011

Negative Differential Conductivity in Carbon Nanotubes in the Presence of an External Electric Field

We study theoretically the electron transport properties in carbon nanotubes under the influence of an external electric field E(t) using Boltzmann's equation. The current-density equation is derived. Negative differential conductivity is predicted when ωτ<<1 (quasi-static case). We observed this in the neighbourhood where the constant electric field E_o is equal to the amplitude of the AC electric field E_1 and the peak decreases with increasing E_1. This phenomenon can also be used for the generation of terahertz radiation without electric current instability.

cond-mat.mes-hall↗

arXiv2010

Direct current generation due to wave mixing in zigzag carbon nanotubes

Generation of direct current in zigzag carbon nanotubes due to harmonic mixing of two coherent electromagnetic waves is being considered. The electromagnetic waves have commensurate frequencies of omega and two omega. The rectification of the waves at high frequencies is quite smooth whiles at low frequencies there are some fluctuations. The nonohmicity observed in the I-Vcharacteristics is attributed to the nonparabolicity of the electron energy band which is very strong in carbon nanotubes because of high stark component. It is observed that the current falls off faster at lower electric field than the case in superlattice. For omega tau equal to two? the external electric field strength Emax for the observation of negative differential conductivity occurs around 1.03x10e6 V/m which is quite weak. It is interesting to note that the peak of the curve shifts to the left with increasing value of omega tau?

cond-mat.mes-hall↗

arXiv2010

Generation of Terahertz Radiation by Wave Mixing in Zigzag Carbon Nanotubes

With the use of the semiclassical Boltzmann equation we have calculated a direct current (d.c) in undoped zigzag carbon nanotube (CN) by mixing two coherent electromagnetic waves with commensurate frequencies i.e and . This effect is attributed to the nonparabolicity of the electron energy band which is very strong in carbon nanotubes. We observed that the current is negative similar to that observed in superlattice. However if the phase shift lies between and there is an inversion and the current becomes positive. It is interesting to note that exhibit negative differential conductivity as expected for d.c through carbon nanotubes. This method can be used to generate terahertz radiation in carbon nanotubes. It can also be used in determining the relaxation time of electrons in carbon nanotubes

cond-mat.mes-hall↗