Detrapping characteristics of an Al_ 2O_ 3/SiO_ 2/4H-SiC stacked structure with two-state trap-assisted tunnelling current behaviour

摘要

The two-state phenomenon induced by trap-assisted tunnelling current was demonstrated to be related to the oxygen vacancy in an Al_ 2O_ 3/SiO_ 2/4H-SiC stacked structure. The device could be set/reset electrically and exhibited two resistive states with appropriate bias voltage. The energy level of the dominant trap extracted from the time variations of gate currents is mainly caused by the oxygen vacancy in the Al_ 2O_ 3 layer, which involves capture and emission of the electron by neutral oxygen vacancy (V~ 0, V~ 0+e~ o→V~ o→V~ 0+e~ -). The gate current representing state 1 changes with time, but even the saturation value can be distinguished from the state 0 current. This indicates that the occupation probability of the dominant traps with electrons remains different than in state 0. Reliable endurance of this device was shown for possible memory application.