Synergistic High Charge-Storage Capacity for Multi-level Flexible Organic Flash Memory.

Minji Kang,Jihong Kim,Juhwan Kim,Dongyoon Khim,Won-Tae Park,Kang-Jun Baeg,Yong-Young Noh,Dong-Yu Kim

doi:10.1038/srep12299

Abstract

Electret and organic floating-gate memories are next-generation flash storage mediums for printed organic complementary circuits. While each flash memory can be easily fabricated using solution processes on flexible plastic substrates, promising their potential for on-chip memory organization is limited by unreliable bit operation and high write loads. We here report that new architecture could improve the overall performance of organic memory, and especially meet high storage for multi-level operation. Our concept depends on synergistic effect of electrical characterization in combination with a polymer electret (poly(2-vinyl naphthalene) (PVN)) and metal nanoparticles (Copper). It is distinguished from mostly organic nano-floating-gate memories by using the electret dielectric instead of general tunneling dielectric for additional charge storage. The uniform stacking of organic layers including various dielectrics and poly(3-hexylthiophene) (P3HT) as an organic semiconductor, followed by thin-film coating using orthogonal solvents, greatly improve device precision despite easy and fast manufacture. Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] as high-k blocking dielectric also allows reduction of programming voltage. The reported synergistic organic memory devices represent low power consumption, high cycle endurance, high thermal stability and suitable retention time, compared to electret and organic nano-floating-gate memory devices.

Highlights

Soaring interests in wearable smart devices have stirred up the development of electronically functional new materials and devices with mechanically flexible/stretchable properties
For a transistor memory device, conductance between the source and drain electrodes is controlled by electric field modulation of the gate electrode either by trapping charge carriers in the gate dielectrics, such as chargeable dielectrics and nano-floating gates (NFGs), or by electric-field-induced and permanent dipoles using ferroelectric materials[24,25,30,32,33,34]
We propose a method to remarkably increase the memory capacity of printed/ flexible organic flash memory via synergistic charge storages composed of chargeable organic materials and NFGs for simultaneous charge trapping at both sites of a single-transistor memory device

Summary

Introduction

Soaring interests in wearable smart devices have stirred up the development of electronically functional new materials and devices with mechanically flexible/stretchable properties. The dual charge trapping sites, referred to here as synergistic memory, provide significantly improved non-volatile memory characteristics compared with common organic transistor memories with a single charge trapping site of either electrets or NFG memories (NFGMs) These characteristics include a wide memory window of ~42.6 V (almost 85.2% of the applied bias), linear shifts in VTh under various gate bias conditions, a multi-level (nine levels per cell) data storage, very reproducible memory cycling endurance during repeated write–read–erase processes (over 100 times), an excellent stability for mechanical bending stress of over 1000 times, and quasi-permanent data retention characteristics (> 108 s)

Methods

Results

Conclusion