Simulation of Quantum Effects and Nonlocal Transport by Using the Hydrodynamic Density-Gradient Model

Seonghoon Jin, Young June Park and Hong Shick Min

We propose a new transport model, named the `hydrodynamic density-gradient (HDG) model', that can simulate the quantum-mechanical and the nonlocal transport effects simultaneously. The HDG model is a hydrodynamic expansion of the density-gradient model that treats the quantum effects by using a quantum correction term. The governing equation set of the HDG model includes the Poisson equation, the electron continuity equation, the quantum potential equation, and the energy balance equation. To discretize the governing equations, we apply the control volume method with nonlinear discretization schemes for the electron and the hole flux terms. To implement the HDG model, we have developed a generalized multi-dimensional device simulator called NANOCAD. We also have implemented other transport models such as the coupled Schr"{o}dinger-Poisson model, the drift-diffusion model, the density-gradient model, and the hydrodynamic model to compare them with the HDG model. We have simulated a 25-nm NMOSFET device, and the results show that our model successfully predicts the quantum-confinement effects, the lateral quantum effects, and the velocity overshoot effects in the device.