Research of current fluctuations of nanoscaled MOSFETs based upon quantum transport models

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In this research project, we have studied the current noise characteristics of nano-scale MOS devices by employing the quantum transport models based upon the nonequilibrium Green's function model (NEGF) and the quantum corrected Monte Carlo (MC) device simulation.1.Quantum corrected Monte Carlo modelThe quantum corrected MC model has been developed to simulate practical semiconductor devices at normal temperatures, and applied to the study of the current fluctuations of a nano-scale Si-MOSFET. The quantum mechanical effects are incorporated in terms of a quantum correction of potential in this particle model. The ellipsoidal multi-valleys of silicon conduction band are also considered in the transport simulation, which is very important in the practical simulation of nano-scaled devices. We have found that the decrease in the number of channel electrons in nano-scale MOSFETs lead to large temporal fluctuations in the electronic current. When the channel length of the devices becomes s … More horter in nano-scale, the transit time of electrons becomes shorter, and the scattering time of electrons also becomes shorter due to the increase of the average energy of electrons, which makes the autocorrelation time of the drain current shorter and consequenrly temporal fluctuations larger.2.Nonequilibrium Green's function modelThe NEGF is used to study the shot noise suppression caused by the quantum mechanical correlations of electrons in semiconductor nano-scale devices, so that the current noise is discussed at low temperature. It was considered interesting to apply the NEGF models to the study of shot noise in ballistic nano-scale Si-MOSFETs, where correlations of electrons are expected to exist when the three dimensional electrons in the electrodes are injected into the inversion layer and confined to quantized subbands as the so-called two-dimentional electron gases. Quantization in the inversion layer and phase coherent transport were anticipated to influence noise performance in ballistic nanoscale Si-MOSFETs. However, up to now, we have not yet observed the shot noise suppression in the simulation of nanoscale MOSFETs. Less