Programmable digital memory devices based on nanoscale thin films of a thermally dimensionally stable polyimide

Abstract

We have fabricated electrically programmable memory devices with thermally and dimensionally stable poly(N-(N',N'-diphenyl-N'-1,4-phenyl)-N,N-4,4'-diphenylene hexafluoroisopropylidene-diphthalimide) (6F-2TPA PI) films and investigated their switching characteristics and reliability. 6F-2TPA PI films were found to reveal a conductivity of 1.0 x 10(-13)-1.0 x 10(-14) S cm(-1). The 6F-2TPA PI films exhibit versatile memory characteristics that depend on the film thickness. All the PI films are initially present in the OFF state. The PI films with a thickness of >15 to <100 nm exhibit excellent write-once-read-many-times (WORM) (i.e. fuse-type) memory characteristics with and without polarity depending on the thickness. The WORM memory devices are electrically stable, even in air ambient, for a very long time. The devices' ON/OFF current ratio is high, up to 10(10). Therefore, these WORM memory devices can provide an efficient, low-cost means of permanent data storage. On the other hand, the 100 nm thick PI films exhibit excellent dynamic random access memory (DRAM) characteristics with polarity. The ON/OFF current ratio of the DRAM devices is as high as 10(11). The observed electrical switching behaviors were found to be governed by trap-limited space-charge-limited conduction and local filament formation and further dependent on the differences between the highest occupied molecular orbital and the lowest unoccupied molecular orbital energy levels of the PI film and the work functions of the top and bottom electrodes as well as the PI film thickness. In summary, the excellent memory properties of 6F-2TPA PI make it a promising candidate material for the low-cost mass production of high density and very stable digital nonvolatile WORM and volatile DRAM memory devices.

Solution-processable triarylamine-based high-performance polymers for resistive switching memory devices

“…98 Excellent WORM memory characteristics are found for films with thicknesses in the range of 34-74 nm, which may be attributed to the formation of stable local filaments. However, DRAM characteristics with ON/OFF current ratios as high as 10 11 are found with film thicknesses of 100 nm because the films are too thick to exhibit stable local filament formation, which is responsible for the DRAM performance.…”

Polymer‐Based Resistive Memory Materials and Devices

“…Interestingly, for polymer P87 (Scheme ), the film thickness can influence the memory behavior . It exhibits excellent WORM memory characteristics for the films with thicknesses in the range of 34–74 nm, which may be attributed to the formation of stable local filament.…”

Synthesis, Morphology, and Properties of Poly(3‐hexylthiophene)‐block‐Poly(vinylphenyl oxadiazole) Donor–Acceptor Rod–Coil Block Copolymers and Their Memory Device Applications

“…Electronic memory devices using polymer materials as active elements have been shown to efficiently store the data based on the high‐ and low‐conductance response to an applied voltage 36–38. Various types of donor‐acceptor material systems have been explored for memory device applications, including conjugated oligomers39–41 or polymers,42, 43 non‐conjugated polymers with donor/acceptor chromophores44–47 and poly­­mer nanocomposites (metal nanoparticle,48, 49 fullerene,50, 51 carbon nanotube43, 52 or graphene oxide embedded53). In general, the memory operating mechanism in such donor‐acceptor systems can be explained by space charges and traps or charge transfer effect as summarized by Kang and co‐workers 38.…”