Tight-binding investigation of electron tunneling through ultrathin SiO2 gate oxides

We investigate electron tunneling through ultrathin gate oxides using scatt ering theory within a tight-binding framework. We employ Si[100]/SiO2/Si[10 0] model junctions with oxide thicknesses between 7 and 18 Angstrom. This a pproach accounts for the three-dimensional microscopic structure of the mod el junctions and for the three-dimensional nature of the corresponding comp lex energy bands. The equilibrium positions of the atoms in the heterostruc ture are derived from first-principles density-functional calculations. We show that the present method yields qualitative and quantitative difference s from conventional effective-mass theory. (C) 2000 Academic Press.