Programmable permanent data storage characteristics of nanoscale thin films of a thermally stable aromatic polyimide

We have synthesized a new thermally and dimensionally stable polyimide, poly(4,4'-amino(4-hydroxyphenyl)-diphenylene hexafluoroisopropylidenediphthalimide)(6F-HTPA PI). 6F-HTPA PI is soluble in organic solvents and is thus easily processed with conventional solution coating techniques to produce good quality nanoscale thin films. Devices fabricated with nanoscale thin PI films with thicknesses less than 77 nm exhibit excellent unipolar write-onceread-many-times (WORM) memory behavior with a high ON/OFF current ratio of up to 10⁶, a long retention time and low power consumption, less than±3.0 V. Furthermore, these WORM characteristics were found to persist even at high temperatures up to 150° C. The WORM memory behavior was found to be governed by trap-limited space-charge limited conduction and local filament formation. The conduction processes are dominated by hole injection. Thus the hydroxytriphenylamine moieties of the PI polymer might play a key role as hole trapping sites in the observed WORM memory behavior. The properties of 6F-HTPA PI make it a promising material for high-density and very stable programmable permanent data storage devices with low power consumption.