Electrically programmable digital memory behaviors based on novel functional aromatic polyimide/TiO2 hybrids with a high ON/OFF ratio

摘要

A novel solution-processable sulfur-containing poly(o-hydroxy-imide) 3SOH-6FPI with pendant hydroxyl groups and the corresponding polyimide 3SOH-6FPI/TiO2 hybrids were synthesized from diamine 4,4'-bis(4-amino-3-hydroxyphenylthio}diphenylsulfide (3SOH-DA) and 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA), and used for memory applications. To enhance the memory behavior, different amounts of TiO2 were introduced into 3SOH-6FPI and the corresponding tunable memory properties were investigated. The hydroxyl groups on the backbone of 3SOH-6FPI could provide reaction sites for organic-inorganic bonding and the homogeneous hybrid thin films could therefore be obtained by controlling the mole ratio of titanium butoxide/hydroxyl groups via sol-gel reaction. The resulting hybrid films having different TiO2 concentrations from 0 wt% to 50 wt% exhibited electrically programmable digital memory properties from DRAM, SRAM, to WORM with a high ON/OFF current ratio (108). Furthermore, from the results of the current-voltage I-V characteristics, the crystalline phase of titania reveals higher trapping ability to increase the retention time in the ON state. In order to get more insight into the switching mechanism of 3SOH-6FPI/TiO2 hybrid memory devices, molecular simulation and electrode effects were also discussed in this study.