• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.759-763
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• 2016

We demonstrate the utilization of ion gel gate dielectrics for operating non-volatile transistor memory devices based on polymer semiconductor thin films. The gating process in typical electrolyte-gated polymer transistors occurs upon the penetration and escape of ionic components into the active channel layer, which dopes and dedopes the polymer film, respectively. Therefore, by controlling doping and dedoping processes, electrical current signals through the polymer film can be memorized and erased over a period of time, which constitutes the transistor-type memory devices. It was found that increasing the thickness of polymer films can enhance the memory performance of device including (i) the current signal ratio between its memorized state and erased state and (ii) the retention time of the signal.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.51-65
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• 2008

The article presents the recent research development in polymer ferroelectric non-volatile memory. A brief overview is given of the history of ferroelectric memory and device architectures based on inorganic ferroelectric materials. Particular emphasis is made on device elements such as metal/ferroelectric/metal type capacitor, metal-ferroelectric-insulator-semiconductor (MFIS) and ferroelectric field effect transistor (FeFET) with ferroelectric poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (TrFE). In addition, various material and process issues for realization of polymer ferroelectric non-volatile memory are discussed, including the control of crystal polymorphs, film thickness, crystallization and crystal orientation and the unconventional patterning techniques.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.46-50
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• 2008

The effect of physicochemical properties of solvents on the microstructure of polyvinyl carbazole (PVK) film for non-volatile polymer memory was investigated. For the solubilization of PVK molecules and the preparation of PVK films, four solvents with different physicochemical properties of the Hildebrand solubility parameter and vapor pressure were considered: chloroform, tetrahydrofuran (THF), 1,1,2,2-tetrachloroethane (TCE), and N,N-dimehtylformamide (DMF). The solubility of PVK molecules in the solvents was observed by ultravioletvisible spectroscopy. PVK molecules were observed to be more soluble in chloroform, with a low Hildebrand solubility parameter, than solvents with higher values. The aggregated size and micro-/nano-topographical properties of PVK films were characterized using optical and atomic force microscopes. The PVK film cast from chloroform exhibited enhanced surface roughness compared to that from TCE and DMF. It was also confirmed that the microstructure of PVK film has an effect on the performance of non-volatile polymer memory.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.237-237
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• 2006

P(VDF/TrFE(72/28) ultrathin films were used in the fabrication of Metal-Ferroelectric polymer-Metal (MFM) single bit device with special emphasis on uniform film surface, faster dipole switching time under applied external field and longer memory retention time. AFM and FTIR-GIRAS were complementary in analyzing surface crystalline morphology and the resultant change in chain orientation with varying thermal history. DC-EFM technique was used to 'write-read-erase' the data on the memory bit in a much faster time than P-E studies. The results obtained from this study will enable us to have a good understanding of the ferroelectric and piezoelectric behavior of P(VDF/TrFE)(72/28) thin films suitable for high density data storage applications.

• 한국전자현미경학회:학술대회논문집
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• 2005.11a
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• pp.80-84
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.440-440
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• 2011

We report on the non-volatile memory characteristics of a bistable organic memory (BOM) device with Au nanoparticles (NPs) embedded in a conducting poly N-vinylcarbazole (PVK) colloids hybrid layer deposited on flexible polyethylene terephthalate (PET) substrates. Transmission electron microscopy (TEM) images show the Au nanoparticles distributed isotropically around the surface of a PVK colloid. The average induced charge on Au nanoparticles, estimated using the C-V hysteresis curve, was large, as much as 5 holes/NP at a sweeping voltage of ${\pm}3$ V. The maximum ON/OFF ratio of the current bistability in the BOM devices was as large as $1{\times}105$. The cycling endurance tests of the ON/OFF switching exhibited a high endurance of above $1.5{\times}105$ cycles and a high ON/OFF ratio of ~105 could be achieved consistently even after quite a long retention time of more than $1{\times}106$ s.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.31-32
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• 2010

In our previous reports [1-3], electron transport for the switching and memory devices using alkyl thiol-tethered Ru-terpyridine complex compounds with metal-insulator-metal crossbar structure has been presented. On the other hand, among organic memory devices, a memory based on the OFET is attractive because of its nondestructive readout and single transistor applications. Several attempts at nonvolatile organic memories involve electrets, which are chargeable dielectrics. However, these devices still do not sufficiently satisfy the criteria demanded in order to compete with other types of memory devices, and the electrets are generally limited to polymer materials. Until now, there is no report on nonvolatile organic electrets using nano-interfaced organic monomer layer as a dielectric material even though the use of organic monomer materials become important for the development of molecularly interfaced memory and logic elements. Furthermore, to increase a retention time for the nonvolatile organic memory device as well as to understand an intrinsic memory property, a molecular design of the organic materials is also getting important issue. In this presentation, we report on the OFET memory device built on a silicon wafer and based on films of pentacene and a SiO2 gate insulator that are separated by organic molecules which act as a gate dielectric. We proposed push-pull organic molecules (PPOM) containing triarylamine asan electron donating group (EDG), thiophene as a spacer, and malononitrile as an electron withdrawing group (EWG). The PPOM were designed to control charge transport by differences of the dihedral angles induced by a steric hindrance effect of side chainswithin the molecules. Therefore, we expect that these PPOM with potential energy barrier can save the charges which are transported to the nano-interface between the semiconductor and organic molecules used as the dielectrics. Finally, we also expect that the charges can be contributed to the memory capacity of the memory OFET device.[4]