Fabrication And Characterization Of Resistive Memories Based On PEDOT:PSS

As advanced technologies develop, the demand for data processing andstorage is increasing dramatically. Resistive memory has the advantages of bothDRAM and Flash as well as the characteristics of thin and small. Resistivememory is a promising candidate for next-generation nonvolatile memoryapplication. Nonvolatile resistive memory based on organic materials has manyadvantages such as low cost, simple process, easy preparation, large-areaapplication and flexibility. PEDOT: PSS is a kind of stable andenvironment-friendly materials, which has been widely used in many fields oforganic electronics. This dissertation attempts to fabricate four types ofnonvolatile resistive memory based on PEDOT: PSS using magnetron sputteringtechnology and spin coating method. We tried to explain the resistanceswitching mechanism in some resistive memory devices, and also discussed thefactors that influenced the performance of resistive memories.Firstly, resistive memory devices with Al/PEDOT:PSS/Al structure exhibitan on/off current ratio as large as104and little degradation after103dcsweeping cycles. The resistance switching mechanism is attributable toformation and rupture of conductive filaments. Besides, we find that the valueof compliant current can effectively control several parameters for resistanceswitching. In addition, the lowest RESET power and the critical compliantcurrent for resistance switching were also determined in Al/PEDOT:PSS/Alresistive memory devices.Secondly, through comparison between Al/PEDOT:PSS/Al,FTO/PEDOT:PSS/Al and Pt/PEDOT:PSS/Al resistive memory devices, wediscussed the influence of bottom electrode on the performance of resistivememories.Finally, we successfully develop a kind of resistive memories with thestructure of Al/PEDOT:PSS/Cu, which exhibits longer retention time (106s),better thermal stability at temperature range of25℃an~d16l0es℃s than2Vthreshold voltage. Also, the resistance switching mechanism inAl/PEDOT:PSS/Cu is due to the existence of Cu filaments, which is confirmed directly using the cross-sectional images of transmission electron microscopyand energy-dispersive X-ray spectroscopy. In addition, we analyzed the causesof failure for Al/PEDOT:PSS/Cu resistive memory at180℃using thetechnologies of XRD, XPS, DSC, TGA and SEM, and came to the conclusionthat the failure was caused by oxidation of Cu top electrode.