Studies On The Resistive Switching Properties Of Cupric Oxide And Titanic Dioxide Nanostructure Films

While traditional memories are approaching their scaling limits, the next generation nonvolatile memory has attracted extensive attention. One of the promising candidates is the resistive random access memory (RRAM) due to its superior characteristics including simple structure, high density integration, low power consumption, and fast write/erase operation. Recently, resistive switching in simple binary transition metal oxide thin films, such as CuO and TiO₂, attracts great interest for a possible application in nonvolatile memory devices. In this letter, we have mostly-investigated the resistive switching properties of CuO nanostructure grain Films and TiO₂ nanostructure mesoporous thin films.In Chapter 2, the copper oxide thin films were deposited on galss floor by ionic sheaf spatter with high temperature annealing method. We have studied the surface morphology, crystalline phases and chemistry value by atomic DFM model of scanning probe microscope (SPM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS).We also have studied its photo switching properties by C-AFM model of scanning probe microscope (SPM).In Chapter 3, we have investigated the hysteretic I-V characteristics of Au/CuO/ Au heterostructures. SCL conduction controlled by Au/CuO interface traps with exponential distribution in energy is employed to describe the carrier transport process. The hysteresis is observed when the carrier trapping level comes to the situation in which the I-V curves show the TFL conduction mechanism, and can be attributed to retention property of trapped carriers. The high and low resistance states induced by voltage pulses are also dependent on the carrier trapping levels and the resistance switching can be regarded as the changes of trap level distribution caused by trapping/detrapping process of hole carriers. This SCL conduction is attributed to interface induced bulklike limited effect because the traps dominating the carrier transport are located at the Au/CuO interface. Carriers filled traps with exponential distribution in energy show the nonvolatile property, which cannot be explained by traditional SCL conduction. The nonvolatility is related to the ordering/disordering transition caused by the trap-assist interface phase separation process of binary transition metal oxide thin films. The present results suggest that the resistance switching of electrode/insulator or semiconductor/electrode sandwich system could be dominated by the defects at the electrode/insulator or semiconductor interface.In Chapter 4, we have investigated the hysteretic I- V characteristics of Au/ TiO₂ mesoporous thin films / Au heterostructures. To our great surprise, we have discovered an abnormality experiment phenomenon different from our former work of CuO nanostructure grain Films and most of the literature report. So far, we are not find out a reasonable theory model to analysis this experiment phenomenon. Maybe wen can figure out it with more lucubrate in the future.