Research On Shot Noise And Transport Mechanism For Nanoscale MOSFET

Experimental observations and simulation results have shown that in short channel devices the carrier transport mechanism shifts from drift diffusive to quasi-ballistic or even to ballistic transport, and the dominant noise source of excess noise changes from thermal noise to shot noise with scaling of MOSFET. The crossover is discussed associated with the same dynamics factors, i.e. the barrier near source and the channel resistance. Based on the physical origins of thermal noise and shot noise and the current flow image, the conversion condition of noise is derived. The shorter the channel, the longer the mean free path, the higher the source-drain voltage, the lower the gate voltage and the lower the temperature, the more easily for the dominant noise source to shift to shot noise from thermal noise. Based on quasi-ballistic current model of nanoscale MOSFET and the generation mechanisms of thermal noise and shot noise, a new current noise model is built, which is very convenient for engineering application. By introducing the role of the Fermi interaction and Coulomb suppression of shot noise, the noise model is modified to predict the current noise of nanoscale MOSFET more accurately. The results of our model coincide well with that has been obtained in previous experiment and simulation. At last, nanoscale MOSFET transport and noise are studied by Monte Carlo simulation and the results show how the transport parameters and noise parameters vary with bias voltage, temperature, and the doping density of source and drain.