The Resistive Switching Of Pr_0.7Sr_0.3MnO₃ Thin Films At Room Temperature

Memory devices are a prerequisite for today's information industry. The semiconductor industry is encountering challenges when device features are approaching the sub-100-nm regime. To overcome the limitations of conventional semiconductor devices, which are based on charge storage, various new nonvolatile-memory (NVM) devices such as magnetic random access memory (MRAM) and phase-change memory (PRAM) and resistance random access memory (RRAM) have been investigated. Of these novel NVMs, the RRAM has become increasingly more attractive for today's semiconductor technology processes due to their drastically reduced power consumption, simple structure, fast switching speed, and nondestructive readouts. This reversible resistance switching (RS) effect has been observed in many insulating or semiconducting systems, including transition-metal oxides, sulfides and organics. Through numerous theoretical models have been proposed, the microscopic origin of RRAM is still not understood.For the same oxide , the resistance switching behaviors are very different. In order to clarify how and where resistance switching occur, we concentred on the resistive-switching properties of perovskite oxides at room temperature. Experimental techniques and conditions are changed to obtain better results. The results are shown as follows:The current-voltage (I-V) characteristics and resistance switching mechanism of Au/ Pr_0.7Sr_0.3MnO₃(PSMO) /Pt sandwiched structures were investigated. The distinct I-V characteristic with pronounced reproducible, nonlinearity, asymmetry was observed at the right condition. The resistive switching behaviors of PSMO films could be well improved and stabilized through post-annealing. The degree of improvement follows the reverse order of the post-annealing temperature. The memory structures exibit low operating voltage (<1 V), showing great promises for low-voltage applications. The surface states induced by the defects act as trap centers of carriers and dominate the I-V characteristics. The conduction mechanism was found to be dominated by the Ohmic behaviour in low resistance states. While the space charge limited conduction controlled by Au/PSMO interface traps was predominant in the high resistance states.The Au/Pr_0.7Sr_0.3MnO₃(PSMO)/FTO sandwiched structure were grown on SnO₂:F (FTO) substates by pulsed laser deposition (PLD) and dc sputtering. X-ray diffraction (XRD) results show that the PSMO thin films exhibited noncrystalline. The results of electrical test indicate that the current -voltage (I-V) curves cound be seen in the negative bias region. Increasing the voltage, the nonliner, asymmetry, and hysteresis cures were observed. The I-V curves intersect with each other at 0 V and -1 V. The I-V properties are controlled by Poole-Frenkel (P-F) and Ohmic type conduction mechanism. The interface state contained high density of defects act as the trap centers of carriers and thus dominate the I-V characteristics.