Nonvolatile WORM memory devices based on polymethacrylate with azoanthraquinone group

Abstract

A novel polymethacrylate containing azoanthraquinone chromophore in the side chain (PMAzoaq6) was synthesized and characterized. An electronic memory device having the indium-tin oxide (ITO)/PMAzoaq6/Al sandwich structure was fabricated and its electrical bistability was investigated. The as-fabricated device was initially found to be at the OFF state and the switching threshold voltage was 1.5 V. After undergoing the OFF-to-ON transition, the device maintains the high conducting state (ON state) even after turning off the electrical power and applying a reverse bias. The device exhibits a write-onceread-many-times (WORM) memory effect with a high ON/OFF current ratio of up to 10 5 and a long retention time in both ON and OFF states, which demonstrated that the synthetic azoanthraquinone-containing polymer possesses a high potential to become polymeric memory devices. WORM, polymer memory, azo, anthraquinone

A low onset voltage WORM type polymer memory based on functional PES

“…And as shown in the DTG curves, the polymers have two main unstable points of 391°C and 446°C because of the degradation of the side chain and the backbone of the polymer respectively, while a tiny weight loss (1%) at a temperature around 150°C was caused by the evaporation of water absorbed on the polymer surface. From all above, the thermal property of CN‐Azo‐PES is comparable with that of polyimides and better than the other polymer materials that have been reported for electrical memory usage . And to the best of our knowledge, in the memory storage processes, the outstanding thermal stabilities will make contributions to the performance of the devices for the absence of thermal decomposition.…”

“…Calculated from the absorption edge of the UV‐vis absorption spectrum in Figure which is 424 nm, the band gap E g (1240/λ edge ) was obtained as 2.92 eV related to the HOMO to LUMO transition of CN‐Azo‐PES, giving a corresponding LUMO energy level of −2.66 eV. When CN‐Azo‐PES is used as the active layer in the electrical memory device, as shown in Figure (b), the energy barrier between HOMO energy level of CN‐Azo‐PES and Φ of ITO (−4.8 eV) is 0.78 eV which is lower than energy barrier (1.62 eV) between LUMO energy level of CN‐Azo‐PES and Φ of Al (−4.28 eV) . Thus, CN‐Azo‐PES is a p‐type material.…”

“…When the device is applied in an electric field, the hole injection from ITO electrode into the HOMO of CN‐Azo‐PES is more preferable than the electron injection from Al electrode into the LUMO of CN‐Azo‐PES. Thus, the switching behavior is ascribed to the charge injection and holes dominate the conduction process …”

“…In particular, the high photosensitivity of the azo dye molecules makes azobenzene polymers popular for use as optical and electronic materials. Also according to the literature, some azobenzene derivatives can be induced by an electric field . Kang and his coworkers have demonstrated that polymers bearing pendent azobenzene chromophores with electron‐accepting terminal moieties exhibit write‐once read‐many (WORM) behavior which is attributed to charge trapping at the azobenzene chromophores and that the device has a low onset voltage .…”

Printed Write Once and Read Many Sensor Memories in Smart Packaging Applications

“…There are many different WORM memory technologies reported in the literature [20], [22], [24], [25], [27]- [29], [32]- [34]. There are also some examples of resistor type memories with multiple read and write functionality (FLASH-type memory) [21], [26], [30], [31].…”