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An analytical model of a possible DNA sensor based on a carbon nanotube network that functions as a selective detector of DNA molecules is presented. The ability to implement label-free electronic detection using a DNA sensor based on a carbon nanotube network constitutes an important step towards low-cost, highly sensitive, simple and accurate molecular diagnostics. In particular, there is an urgent need for a simple method of detection of DNA molecules as this will provided a new and efficient way to diagnosis genetic or pathogenic diseases. Bio-compatibility and high sensitivity towards environmental perturbations make graphene nanomaterials a good choice for a sensing layer in an electronic DNA sensor. In this study, a conductance model of a DNA sensor based on a carbon nanotube network is suggested and the performance of the model is evaluated by calculating current-voltage characteristics. [ABSTRACT FROM AUTHOR]

In this work, fundamental results on carrier statistics in a carbon nanotube treated as a one-dimensional material are presented. Also the effect of degeneracy on the capacitance of the carbon nanotube channel in a carbon nan-otube field effect transistor is discussed. A quantum capacitance as well as a classical capacitance is revealed. Furthermore it is shown that for low gate voltage, the total capacitance is equivalent to the classical capacitance but for high gate voltage it is equivalent to the quantum capacitance. We predict that in the nondegenerate regime, the total capacitance is equivalent to the classical capacitance and that the quantum capacitance can be neglected, whereas only quantum capacitance needs to be taken into account in the calculation of the total capacitance in the degenerate regime. [ABSTRACT FROM AUTHOR]

The band structure of a carbon nanotube (CNT) near to the minimum band energy is parabolic. However it is not parabolic in other parts of the band energy. In the parabolic part, based on the confinement effect, we present an analytical model that captures the essence of the physical processes relevant to the operation of a carbon nanotube field effect transistor (CNTFET). The model covers seamlessly the whole range of transport from drift-diffusion to ballistic. It has been clarified that the intrinsic speed of CNTs is governed by the transit time of electrons. Although the transit time is more dependent on the saturation velocity than on the weak-field mobility, the feature of high-electron mobility is beneficial in the sense that the drift velocity is always maintained closer to the saturation velocity, at least at the drain end of the transistor where the electric field is necessarily high and controls the saturation current. The results obtained are applied to the modeling of the current-voltage characteristics of a CNTFET. The channel-length modulation is shown to arise from the drain velocity becoming closer to the ultimate saturation velocity as the drain voltage is increased. [ABSTRACT FROM AUTHOR]