M. Depas et al., DETERMINATION OF TUNNELING PARAMETERS IN ULTRA-THIN OXIDE LAYER POLY-SI SIO2/SI STRUCTURES/, Solid-state electronics, 38(8), 1995, pp. 1465-1471
In this work the electron tunnelling in device grade ultra-thin 3-6 nm
n(+)poly-Si/SiO2/n-Si structures has been analysed. The well known an
alytic expression for the Fowler-Nordheim tunnelling current was adapt
ed to include the case of direct tunnelling of electrons, which become
s important for oxide layers thinner than 4.5 nm. For these ultra-thin
oxide MOS structures it is necessary to take the band bending in the
Si substrate and in the poly-Si layer into account to determine the ox
ide electrical field strength acid to derive the tunnelling parameters
of the measured current-voltage characteristic. A method is explained
to derive the tunnel barrier height phi(s) and the effective mass of
the tunnelling electron m(ox) from the experimental tunnel current cha
racteristics. It is shown that both the direct tunnelling and the Fowl
er-Nordheim tunnelling current can be quantitatively explained by a WK
B approximation using m(ox) as the single fitting parameter.