Electric-Controlled Resistive Switching and Different Synaptic Behaviors in p⁺-Si/n-ZnO Heterojunction Memristor

In this study, the resistive switching (RS) and different synaptic behaviors have been observed by controlling the different applied bias voltages in the p+-Si/n-ZnO heterojunction memristor. After a big forming voltage, the formation and rupture of the oxygen vacancy filaments model has been proposed, and different migration amount of oxygen ions realizes the multiple RS behaviors. Prior to the electroforming, different synaptic behaviors have been observed dependent on the applied bias voltage based on the oxygen ion migration processes. Under small bias (<2.5 V), the oxygen ion of ZnO film first migrates and inters into p/n-junction barrier region, leading to the increasing barrier height/width. With increasing voltage, the electric field will further induce oxygen ion migration and entrance to Si film, leading to the decreasing barrier height/width. Several synaptic functions are demonstrated, such as nonlinear transmission characteristics, long-term memory (LTM)/short-term memory (STM) and “learning-experience” behavior. Multifunction memristive behaviors and these mechanisms research are important to design and realize the multifunction devices for decreasing the manufacturing complexity.