Simulation of current fluctuations in submicron n-MOSFETs operating in the hot-carrier regime at RF frequencies using two-dimensional impedance field method

Abstract

We simulate transport and fluctuations in 0.3 µm gate length n-MOSFETs operating in the hot-carrier regime using ISE-TCAD software. Our results are compared with other results given by microscopic simulations. As a first step, drift-diffusion and hydrodynamic models are employed to study the static and dynamic characteristics of these devices in common-source configuration. The velocity overshoot and other hot electron phenomena in the pinch-off region of the channel as well as the admittance parameters and other elements of small-signal equivalent scheme are in good agreement with the results of Monte Carlo simulations. The calculation of the spectral density of current fluctuations is implemented within the two-dimensional direct impedance field method of ISE-TCAD software at RF frequencies, when current fluctuations are dominated by diffusion noise. Among the two macroscopic models, only the hydrodynamic scheme simulates correctly the excess noise due to the presence of hot carriers.