A reduced mesh quality dependency simulation method for carrier transport simulation with density gradient quantum correction

Abstract

The density gradient model is a drift–diffusion approximation with density gradient quantum correction, which can be employed for carrier transport simulation in high quantum confinement regions with rapid computation speed and accurate simulation results. The utilization of the finite volume method (FVM) in solving the density gradient model will lead to an overestimation of control volume of nodes in obtuse triangle meshing grids, which can introduce errors or even generate non-physical results in the simulation of device characteristics, such as carrier concentration, current, and capacitance. In this paper, an improved method is proposed to increase the simulation accuracy of the density gradient model in obtuse triangle meshing grids, where the control volume discretization is corrected by using centroids of meshing grids instead of circumcenters, and a vector finite element method is employed to compute the carrier flux of control volumes. A carrier transport simulation on a double-gate MOSFET with density gradient quantum correction on meshing grids with different qualities is performed to validate the accuracy of our proposed method. The impacts of obtuse triangle meshing grids on the carrier distribution, drain current-gate voltage (ID-VG) characteristics and gate capacitance-gate voltage (CG-VG) characteristics of double-gate MOSFET simulated by FVM and our proposed method are compared and analyzed in detail. The simulation results demonstrate that our improved method could reduce the dependence on the quality of meshing grids in carrier transport simulation within high quantum confinement regions.