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 SiO2-Si3N4interface to the Si conduction band, 2) from the Si3N4layer to the Si conduction band (directly), and 3) from the Si3N4layer to the interface (and then to the Si conduction band). The trapped electron densities at the interface and in the Si3N4layer axe investigated analytically and numerically. It is found from the analysis that the process 3) is dominant in transferring the electrons in the Si3N4layer to the Si conduction band. Furthermore, a physical interpretation for the maximum tunneling distance obtained in the previous work is given in details.