Application of density-gradient model to nanoscale MOS structures

The density-gradient (DG) model as a generalized drift-diffusion (DD) model is applied to investigate the quantum confinement in MOS structure. Both of the electron and hole profiles are calculated for the entire structure using the DG model. The electron effective mass fitting is made by comparing with the calculation from Schrodinger-Poisson (SP) model in which up to 40 subbands are accounted, yielding a electron effective mass of m_n* = 0.27 m_o. The quantum confinement is observed in both the inversion layer and poly-gate layer. The variation in quantum potentials and the shift in threshold voltage are also presented.