Abstract
In this paper we present a physics-based model for hot carrier surface mobility in semiconductor devices and sensors which incorporates the band structure and interface/surface effects. This model can be utilized within the generalized hydrodynamic model (HDM), for semiconductor device and sensor simulation [1]. The proposed non-local surface mobility model is essentially needed in the hydrodynamic transport modelling of hot carriers as an energy-dependent model. Unfortunately, most of the involved parameters in the hydrodynamic simulation of semiconductor devices and sensors are obtained from Monte Carlo simulation in the bulk of a homogenous semiconductor. However, the correct simulation of the dynamic behaviors of hot carrier transport across semiconductor surfaces and junctions, needs to consider the main variable gradients, such as the carrier density, energy (or temperature) and velocity gradients. In particular, the velocity gradient plays a significant role in the transport of hot carriers in 2D electron/hole gas devices. Therefore, our mobility model focuses on the role of velocity gradients of hot carriers and the underlying carrier gas viscosity, to interpret the well-known surface mobility reduction, near the Si/SiO2 interface in nano devices and nano sensors. Unlike previous surface mobility models, which are primarily based on the local electric field and fitting of experimental data, our model is physics-based on the hot carrier energy and velocity gradients. Therefore, our model is also considered truly non-local and fully hydrodynamic.
![Electron drift mobility in the homogenous bulk of undoped silicon at 300K, versus electron average energy, according to our model. The energy relaxation time of electrons in Si, is plotted on the secondary axis, as a function of electron energy according to [39].](https://www.igminresearch.com/articles/figures/igmin305/igmin305.g001.png)
![Comparison between the new mobility model at the Si/ SiO2 interface of an n-MOSFET and some published data at different substrate doping, versus effective surface field [23,41]. All data sets at Vsub=0, except the last one at Vsub= -3V.](https://www.igminresearch.com/articles/figures/igmin305/igmin305.g004.png)
