Nonvolatile memory characteristics of organic thin film transistors using poly(2-hydroxyethyl methacrylate)-based polymer multilayer dielectric

Abstract

A wide hysteresis width characteristic (memory window) was observed in the organic thin film transistors (OTFTs) using poly(2-hydroxyethyl methacrylate) (PHEMA)-based polymer multilayers. In this study, a strong memory effect was also found in the pentacene-based OTFTs and the electric characteristics were improved by introducing PHEMA/poly(methyl methacrylate) (PMMA)/PHEMA trilayer to replace the conventional PHEMA monolayer or PMMA/PHEMA and PHEMA/PMMA bilayer as the dielectric layers of OTFTs. The memory effect was originated from the electron trapping and slow polarization of the dielectrics. The hydroxyl (-OH) groups inside the polymer dielectric were the main charge storage sites of the electrons. This charge-storage phenomenon could lead to a wide flat-band voltage shift (memory window, △VFB = 22 V) which is essential for the OTFTs’ memory-related applications. Moreover, the fabricated transistors also exhibited significant switchable channel current due to the charge-storage and slow charge relaxation.

Negative Differential Resistance Behavior and Memory Effect in Laterally Bridged ZnO Nanorods Grown by Hydrothermal Method

“…As conventional flash memories approach their technological and physical limits in scaling reduction, resistive random access memory (ReRAM) has been attracting much attention because of its many advantages, such as simple structure, high density integration, high operational speed, low-power consumption, and potential for the replacement of flash memories in next-generation nonvolatile memories. − RS behaviors have been extensively investigated in various materials, such as binary transition metal oxides, − perovskite oxides, , organic compounds, − and graphene oxide, among others. To explain the RS phenomenon, researchers have proposed many theoretical models.…”

Bipolar resistive switching based on bis(8-hydroxyquinoline) cadmium complex: Mechanism and non-volatile memory application

“…[7,8] The memory effect has been demonstrated in various device architectures, such as a single organic layer and multiple organic-inorganic layers sandwiched between two electrodes. Various kinds of organic materials are reported as the single layer in NVMs, such as small molecules, [9][10][11][12][13][14][15] conjugated polymers, [16][17][18][19][20][21] polymer blends, [22,23] copolymers, [24,25] polymer-metal nanopartical blended structures, [17,26,27] conjugated polymer-donor-acceptor blends, [28] and molecules embedded in a superamolecular matrix. [29] The typical organic multilayers used in resistive switching devices include the trilayers of organic molecules/metal nanoparticles/organic molecules, [9,[30][31][32] organic molecules/coreshell nanoparticles/organic molecules, [33] and semiconducting molecules/insulating molecules/semiconducting molecules, [34] and the bilayers of inorganic salt/molecules [35] and metal oxides/polymers.…”

Investigation of Nonvolatile Memory Effect of Organic Thin-Film Transistors with Triple Dielectric Layers

“…In this report, we proposed that the memory effect was due to the locally trapped charges and slow polarization that induce a memory window. 12,13) Here, hydroxyl (-OH) groups can be considered as electron trap sites. 12,14) When a large positive gate voltage was applied, electrons were trapped in hydroxyl groups of PHEMA near the channel and accumulated in the channel layer 15) and holes were detrapped from PHEMA close to gate electrode.…”

“…12,13) Here, hydroxyl (-OH) groups can be considered as electron trap sites. 12,14) When a large positive gate voltage was applied, electrons were trapped in hydroxyl groups of PHEMA near the channel and accumulated in the channel layer 15) and holes were detrapped from PHEMA close to gate electrode. 16,17) This trapping process resulted in the generation of the built-in electric field in dielectric layers.…”