Abstract EN:

The development of new electronic devices from carbon-based nano materials (graphene, nanoribbons, nanotubes) opens attractive perspectives. Most of the devices, mainly field effect transistors (MOSFETs), are based on classical structures where the channel consists of a unidimensional carbon nanotube which has much higher transport properties than silicon. A common feature of many carbon nanotube MOSFETs (CNTFETs) is the existence of a Schottky barrier at the nanotube-metal interface of source and drain contacts. So, in the thesis, I have developed a model to take into account Schottky contacts in semiclassical Monte Carlo simulation of CNTFETs. The static and dynamic performances are analysed as a function of material parameters and structure geometries such as Schottky barrier height at metal-nanotube interface, gate length, gate oxide thickness, and nanotube diameter. Moreover, we compare the performances with those of ohmic contact devices. We present then a detailed analysis of transport in the channel of ohmic contact carbon nanotube transistors. Firstly, a strong ballisticity is obtained from classical simulation. It leads naturally to study the influence of quantum transport on microscopic and macroscopic transistor behaviours by the Wigner Monte Carlo formalism. Comparisons between microscopic results from Boltzmann formalism and Wigner formalism show the existence of coherent phenomena in CNTFETs. Meanwhile we notice that at macroscopic scale the difference between Wigner and Boltzmann currents is weaker when the gate length decreases. In fact, for smaller gate length, the source-drain tunnelling effect partly compensates quantum reflection at the end of the channel while the latter depends weakly on the gate length. That is the reason why the classical and quantum currents become quite similar.