A new mobility model dependent upon electron concentration is presented for studying the screening effect on ionized impurity scattering. By coupling this model with the drift-diffusion and Hartree models, the effects of self-consistent and quasi-equilibrium screening on carrier transport in heavily doped systems are revealed for first time. The transport mechanism is found to be dominated by the electron-concentration-dependent mobility, and transconductance is shown to be determined by effective mobility and changes from degraded to enhanced characteristics with electron concentration modulation.

A unified model for frequency-dependent characteristics of transconductance and output resistance is presented that incorporates the dynamics of quasi-Fermi levels. Using this model, multiple-frequency dispersion and pulse-narrowing phenomena in GaAs MESFETs are demonstrated based on the drift-diffusion transport theory and a Schockley-Read-Hall-type deep trap model, where rate equations for multiple trapping processes are analyzed self-consistently. It is shown that the complex frequency dependence is due to both spatial and temporal effects of multiple traps.

A new multi-phonon model for hydrogen desorption at Si/SiO2 interface due to hot carriers is proposed for a multi-scale simulation, in which Lattice Monte Carlo method is coupled with Device Monte Carlo method by using a mediator-based common software platform. The power law between interface trap density and time (Nit tα) of which power α =0.5 is demonstrated and shows good agreement with experimental results. Dependence of Vth shift on the current stress time is analyzed accurately by introducing an electron trap model. According to the multi-phonon mechanism, it is found that hot carriers will generate defects on the gate dielectrics in 13 nm gate device under low operation voltage of Vd=0.5 V but density of interface traps after long stress time is suppressed to 1015 m-2.