Study Of The Resistance Switching Effects At Layered Perovskite Oxides PrBa₂Cu₃O_xand Pr₂CuO₄Ceramics

The rapid development of information technology today, the performance of non-volatile memoryrequirements are also increasing. Within a decade or two, the improvement of the performance ofsilicon-based electronic memories is expected to nearly reach its limits. This is motivating people activelyin the search for new materials that may become alternative technologies. Among the most promisingcandidates, the resistive random access memory (RRAM) is found with capacitor-likemetal/transition-metal oxide/metal structures. It mainly consists of the sudden change of the resistance ofthe system upon an electric voltage excitation applied on the electrodes. The main features are that theinduced changes are non-volatile and reversible. The EPIR effect has already been reported in systems witha lot of transition-metal oxides as the dielectric. With the final goal of achieving electronic deviceimplementations, most of the work has focused on the behavior of the film at room temperature. However,it has also been observed in block ceramic dielectrics. Many studies report on evidence which indicates thatthe effect occurs in regions of the dielectric near the electrode interfaces: nevertheless, there is still not aconsistent opinion on the physical origin of the switching mechanism. In this paper, the resistanceswitching effect is demonstrated in the perovskite copper oxide PrBa2Cu3Ox(PBCO) and Pr2CuO4(PCO)system, where the dielectrics are the materials loss of superconductivity in high-temperaturesuperconductors. The present work is helpful to elucidate the physics origin of resistance switching effect.A bulk dielectric is considered that can study the switching of the interfaces and bulk behaviorindependently by means of a multi-electrode method.In this paper, the resistance switching effect is demonstrated in the perovskite copper oxidePrBa2Cu3Ox(PBCO) and Pr2CuO4(PCO) system, including the following aspects:s1. Preliminary study of the resistance switching effect at PBCO systemThe EPIR effects take place at the Pt/PBCO/Pt plane memory devices. Additionally, withinvestigation further the R-T curve of bulk resistance, the results indicate that the EPIR effect is mainlyinduced and dominated by the change of interface resistance, rather than the bulk resistance. To gainfurther insight into the physics origin of EPIR effect at PBCO system, Ag/PBCO/Ag device is prepared, which shows a more stable EPIR effects. Two devices have a biggest difference point, Pt/PBCO/Ptwrite voltage is+10V, however, Ag/PBCO/Ag write voltage is-10V, and the erase voltage is opposite.This situation requires further exploration, as well as the physics origin of EPIR effects also need to studyfurther.2. Study of the resistance switching effect at Pt/PBCO/Pt systemPt/PBCO/Pt device shows the EPIR effect afrer the application of5V amplitude pulses with alternatepolarities, and very stable retention characteristics. The write voltage+5V and-5V are tested, and in bothcases the pulse voltage polarity is dependent bipolar, has high stability and retention. Followed by afour-wire PBCO body resistance and temperature measurement relationship testing to further validate theEPIR effect is mainly due to Pt and PBCO interface plays a major role. This chapter highlights is to explorethe role of each interface, using three line method for simultaneous measurement of the1interface,4interface, and the resistance change of14interface under pulse voltage. The results find that the previoustwo cases on the surface are the opposite situation, but actually resistance change of the two interfaces1and4in the positive and negative pulse voltage generated the effect is the same. For example, the1interface is induced the low resistance state under the positive pulses both the two cases, the negative pulseis just the opposite. According to the characteristics of I-V curve of an interface under the high and lowresistance, the schematic of the interface is drawn. Carrier injection model should be able to explain theEPIR effect, it can adjust the resistance near the interface, under high resistance state, interfaces state mayinstead of the inside Schottky-like barrier, the interface layer plays an important role.3. Preliminary study of the resistance switching effect at PCO systemThe electrodes In, Au and Pt is prepared on the surface of PCO ceramic, consist of In/PCO/In,In/PCO/Au, Au/PCO/Au and Pt/PCO/Pt four-type devices. All of the devices are measured havingabnormal bipolar resistive switching properties under the two-wire method using the Keithley2400sourcemeter. The resistance switching properties is the main interface effects produced by the formationand migration of oxygen vacancies, which modify the barrier height and the depletion layer width.