2.3 Drift-Diffusion Transport Model

The DD model is the simplest current transport model which can be derived from the BTE by assuming that the electron temperature is equal to the lattice temperature. According to this approach the local temperature of the carrier gas can be estimated via the homogeneous energy balance equation

(2.16)
where τE is the energy relaxation time. Consequently
(2.17)
The substitution of (2.17) in (2.12) and (2.13) gives us
(2.18)
(2.19)

where the net generation rate G. This approach for the BTE solution had been the mainstay for modeling transport in industrial applications for over thirty years. However, it should be noted that modeling of deep-submicron devices employing DD model is becoming more and more problematic. As long as the device channel length exceeds ~120nm, the simplified Drift-Diffusion and Hydrodynamic schemes for BTE solving are believed to be well-suited [156]. However, due to continuous device miniaturization these approaches fail for the description of ultra-scaled MOSFETs and thus a direct solution of BTE is pursued.



I. Starkov: Comprehensive Physical Modeling of Hot-Carrier Induced Degradation