The Study Of Two-terminal Organic Resistive Nonvolatile Memory Devices Based On Bis (8-hydroxyquinoline) Cadmium

Information technology and the internet of things (IOT) are developing rapidly in 21th century in which memory, one of the most important element of them are playing an important role. Compared with inorganic counterpart, organic resistive switching memory devices has not only the advantage of high storage density, high speed and good technological compatibility, but also the ability to be made on variety of light, ultrathin and large area cheap substrates, which make them competitive in applications in information and IOT technology.This thesis gives brief introduction to the classification and recent development of two-terminal organic resistive switching memory devices as well as their typical structure, fabrication method and mechanism of resistive switching. The fabrication, properties and resistive switching mechanism of two-terminal devices based on bis(8-hydroxyquinoline) cadmium (Cdq2) are described in great detail. Stable and persistent bipolar resistive switching and negative differential resistance are observed in the first time and non-volatile memory characteristics are demonstrated in organic diodes with a structure of "indium tin oxide (ITO)/ Cdq2/Al". Aggregate formation and electric field driven trapping and detrapping of aggregate states lie in the energy gap of HOMO and LUMO of the organic molecule are proposed as the mechanism of the observed bipolar resistive switching. AFM images show that large particles formed by aggregation of Cdq2 molecules are uniformly scattered in the active film, which gives solid support for the proposed mechanism. Further studies show that devices with the structure of "ITO/Cdq2/Al nano prticle/Al" and "ITO/Cdq2/Cdq2:PTCDA/Al", where PTCDA denotes 3,4,9,10-perylenete-acarboxylic dianhydride, exhibit better stability.