Multilevel Schottky Barrier Nanowire SONOS Memory With Ambipolar n- and p-Channel Cells

A novel multilevel Schottky barrier nonvolatile nanowire memory is experimentally reported with low-voltage operations and excellent reliability. Using efficient hot-electrons and hot-holes generation associated with Schottky barrier source/drain, the multilevel schemes of silicon nanowire silicon-oxide-nitride-oxide-silicon (SONOS) cells are achieved at adequately low gate voltages. The n-channel cells work at a small gate voltage of 5 to 7 V using multilevel electron programming, whereas the p-channel cells operate at a low gate voltage of -7 to -11 V using multilevel hole programming. The roles of electron and hole carriers in the n-channel cells are exchanged in the p-channel nanowire cells because of ambipolar conduction. Both the n- and p-channel multilevel Schottky barrier nanowire SONOS cells preserve excellent thermal retention and cycling endurance for use in practical embedded and stand-alone nonvolatile memories.