Tunneling through ultrathin SiO2 gate oxides from microscopic models

We investigate theoretically coherent electron tunneling through three-dime nsional microscopic Si[100]/SiO2/Si[100] model junctions with oxide thickne sses between 0.4 and 4.6 nm. The transmission probabilities of these struct ures were calculated using a semiempirical tight-binding scattering method. Our calculations provide a basis for the microscopic understanding of the observed independence of tunneling transmission on the orientation of the b ulk silicon and on the nature of inelastic defect-assisted tunneling. We do cument significant differences between transmission coefficients obtained w ith the present scheme and with the popular effective-mass-based approaches . The energy dependence of the effective tunneling mass in bulk silicon dio xide is predicted. (C) 2001 American Institute of Physics.