Towards a full microscopic approach to the modeling of transistors with nanometer dimensions

Metal oxide semiconductor field-effect transistors with channel lengths in the nanometer range have recently been the subject of many new modeling and simulation approaches. Unfortunately, semi-classical methods currently used in microelectronics are not suitable to describe accurately all physical effects when device integration approaches atomic scale. The aim of this study is to compare theoretical results obtained from different atomistic approaches with those classically deduced with the effective mass approximation. We calculated the transmission coefficient in the simple case of linear atomic chains or of several coupled chains by successively considering: (i) the effective mass approximation, (ii) a direct calculation of semi-infinite chains transmission using a simple one band tight binding approximation, (iii) the diffusion theory in the Green’s functions formalism expressed in the frame of tight binding. This last method offers several advantages since it is able to capture the essential physics of nanoscale devices (electron–electron and electron–phonon interactions). Finally, we summarize the discussion of the extension of this last approach to realistic devices.