Current-voltage characteristics of Al/SiO2/p-Si MOS tunnel diodes with a spatially nonuniform oxide thickness

Abstract

The effect of nonuniform distribution of the insulator thickness on the behavior of Al/SiO2/p-Si MOS tunnel structures with a (1–4)-nm-thick insulator is studied. The character and magnitude of the effect depend on the applied bias. In any conditions, the nonuniformity of the SiO2 thickness enhances the total through currents as compared to those flowing across a uniform oxide layer of the same nominal thickness. Further, the potential of the inversion layer changes in the inversion mode. The calculations performed take into account the tunnel transport between the Si conduction band and the metal, that between the Si valence band and the metal (including in the inversion mode, the resonant transport, which is less clearly pronounced because of the thickness nonuniformity), and the band-to-band tunneling in the semiconductor.