Characterization and modelling of carrier distribution and gate capacitance in MOS structure inversion layer

Abstract

Based on the carrier distribution in three-dimensional semi-classical and twodimensional quantum mechanical cases, the concept of surface layer effective density-of-states (SLEDOS) is proposed. Then a simplified method of calculating the band bending and subband energies is employed to investigate quantum mechanical effects (QMEs) in MOS structure inversion layer. The method is unique compared with published methods in its reversed nature of the iteration procedure. It has high efficiency and good convergence characteristics and gives satisfactorily coincident results with rigorous but more complicated selfconsistent calculations. The method is applicable in both quantum mechanical and semi-classical cases. The subband occupation of inversion layer carrier and the two-dimensional density-of-states in semi-classical and quantum mechanical cases are then calculated. QMEs on inversion layer carrier density and surface potential are analysed on the basis of the method. Gate capacitance in the MOS structure inversion region is formulated for both quantum mechanical and semiclassical cases, and QMEs on gate capacitance are analysed.