Discharging process by multiple tunnelings in thin-oxide MNOS structures

A theoretical calculation is carried out on a discharging process in thin-oxide MNOS (metal-nitride-oxide-semiconductor) structures by proposing multiple and composite tunnelings. In this analysis three tunneling processes are considered: 1) from the SiO
2
-Si
3
N
4
interface to the Si conduction band, 2) from the Si
3
N
4
layer to the Si conduction band (directly), and 3) from the Si
3
N
4
layer to the interface (and then to the Si conduction band). The trapped electron densities at the interface and in the Si
3
N
4
layer axe investigated analytically and numerically. It is found from the analysis that the process 3) is dominant in transferring the electrons in the Si
3
N
4
layer to the Si conduction band. Furthermore, a physical interpretation for the maximum tunneling distance obtained in the previous work is given in details.