This study demonstrates a new and realizable possibility of 1T-type ferroelectric random accessmemory devices using an all solution processing method with cellulose paper substrates. A ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin film was formed on a paper substrate with an Al electrode for the bottom-gate structure, and then a semiconducting poly(3-hexylthiophene) (P3HT) thin film was formed on the P(VDF-TrFE)/paper structure using a spincoating technique. The fabricated ferroelectric gate field-effect transistors (FeFETs) on the cellulose paper substrates demonstrated excellent ferroelectric property with a memory window width of 20 V for a bias voltage sweep from -30 to 30 V, and the on/off ratio of the device was approximately 10(2). These results agree well with those of the FeFETs fabricated on a rigid Si substrate. In order to compare and check the reproducibility of the characteristics of the FeFETs on the paper substrate, it also has been attempted to make FeFETs with various channel length and width ratios were fabricated. From the measured characteristic results, it can be seen that the electrical properties of FeFETs are almost similar regardless of the substrate type. These results will lead to the emergence of printable electron devices on paper. Furthermore, these nonvolatile paper memory devices, which are fabricated by a solution processing method, are reliable, very inexpensive; have a high density; and can be fabricated easily.

The flexible organic non-volatile ferroelectric field-effect transistors (FeFETs) with poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] was fabricated on polyimide and aluminum foil substrates. Al foil has merit of flexibility because of ultraflexible and ultrathin properties. It can be bent with small bend radius and even folded. It serves as bottom gate electrode in itself aswell. Thus, an expensive fabrication step, evaporation of bottom gate, can be removed. In spite of these merits of Al foil, it is difficult to fabricate FeFETs on it owing to difficulty in handling: Al foil wrinkles easily and cannot be flattened during fabrication. The regioregular poly(3-hexylthiophene) [P3HT] film was formed as an active layer by the sol-gel method at lowtemperature. In case of the fabricated FeFETs on polyimide substrates, the field-effect mobility was similar to 0.28 cm(2)/Vs, the on/off ratio was approximately 5.6 x 10(3), and the memory window (threshold voltage shift) was approximately 7 V. It has similar to 10(3) of current on/off ratio and about 7-8 V of memory window for the Al foil substrates.

Paper transistors have the advantages of recyclability, high abundance, low cost, disposability, and biodegradability. In this paper, a nonvolatile transistor fabricated on a paper substrate without protective layers by using solution-based methods is presented, and promising performance is reported. The memory window of ferroelectric field-effect transistors is approximately 16 V when the gate voltage is swept from +20 V to -20 V. The on/off ratio is 3.45 × 10 2 , even on the paper substrate. Electrical characteristics of the memory device are not degraded, as compared with those of transistors on rigid substrates fabricated simultaneously.

In this study, we fabricated blended PVDF-P(VDF-TrFE) solutions at different concentrations and formed ferroelectric films via the sol gel method. We then worked with organic ferroelectric field-effect transistors featuring ferroelectric polymer (PVDF/P(VDF-TrFE)) blended films and a poly-3-hexylthiophene(P3HT) organic channel on a TiN substrate. Finally, electrical and ferroelectric properties were compared to those of pure P(VDF-TrFE) and blended PVDF/P(VDF-TrFE) films.

We fabricated metal-ferroelectric-metal capacitors and bottom-gate, top-contact nonvolatile ferroelectric transistors (FeFETs) using poly( vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and poly(3-hexylthiophene) (P3HT) on aluminum foil substrates. P(VDF-TrFE) and P3HT layers were formed by the sol-gel method at low temperature. FeFETs on Al foil substrates exhibited similar properties compared with those fabricated on other rigid and flexible substrates.

This study demonstrates a new and realizable possibility of 1T-type ferroelectric random access memory devices using an all solution processing method with cellulose paper substrates. A ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin film was formed on a paper substrate with an Al electrode for the bottom gate structure, and then a semiconducting poly(3-hexylthiophene) (P3HT) thin film was formed on the P(VDF-TrFE)/paper structure using a spin-coating technique. The fabricated ferroelectric gate field effect transistors (FeFETs) on the cellulose paper substrates demonstrated excellent ferroelectric property with a memory window width of 20 V for a bias voltage sweep from -30 to 30 V, and the on/off ratio of the device was approximately 10(2). These results agree well with those of the FeFETs fabricated on a rigid Si substrate. These results will lead to the emergence of printable electron devices on paper. Furthermore, these non-volatile paper memory devices, which are fabricated by a solution processing method, are reliable, very inexpensive, have a high-density, and can be fabricated easily.

In this work, metal-ferroelectric-semiconductor field-effect transistors (MFSFETs) have been fabricated for the first time using poly(vinylidene fluoride) (PVDF) and polyvinylidene fluoride trifluoroethylene [P(VDF-TrFE)] thin films as ferroelectric layer. PVDF and P(VDF-TrFE) thin films were fabricated by sol-gel method on Si(100) wafers. The drain current-gate voltage (ID-VG) characteristics of the fabricated MFSFETs with PVDF and P(VDF-TrFE) thin films exhibited very good ferroelectric hysteretic curves with counterclockwise loop same to those of other ferroelectric materials. It also demonstrates a realizable possibility of one-transistor type (1T-type) ferroelectric memory without a buffer layer using thin organic material. The absence of a buffer layer presents many advantages such as the elimination of the depolarization field, leakage current influence of the thin buffer layer, reduction of the process steps, low-operational voltage, and low-power consumption. The MFSFETs using PVDF and P(VDF-TrFE) thin films as ferroelectric layer have promising potential for use in low-voltage operable and flexible 1T-type ferroelectric random access memory (FeRAM) using organic material. On the other hand, it also has been attempted tomake ferroelectric field-effect transistors (FeFETs) with blended PVDF/P(VDF-TrFE) films in order to compare the P(VDFTrFE) films. The ferroelectric films for metal-ferroelectric-metal (MFM) capacitors have been fabricated using the blended PVDF/P(VDF-TrFE) solutions with different concentrations by sol-gel method. Ferroelectric field-effect transistors using poly(3-hexylthiopene) (P3HT) channel layer have also been fabricated on TiN substrates in order to compare the device characteristics of the pure P(VDF-TrFE) and blended PVDF/P(VDF-TrFE) thin films in this study.

We fabricated ultra-flexible organic non-volatile ferroelectric field-effect transistors (FeFETs) with poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] on polyimide substrates, which adopted a solution-based top-contact/bottom-gate structure for low cost process without patterning. P(VDF-TrFE) gate dielectric layers and regioregular poly(3-hexylthiophene) active layers were formed by the spin-coating method. The field-effect mobility (μFE) was ∼0.28 cm2/V s, the on/off ratio was approximately 5.6 × 103, and the memory window (threshold voltage shift) was approximately 7 V. In addition, FeFETs were operated even at small bend radii without considerable changes in these values.

This book provides comprehensive coverage of the materials characteristics, process technologies, and device operations for memory field-effect transistors employing inorganic or organic ferroelectric

We fabricated a metal-ferroelectric-insulator-semiconductor structure using a poly(vinylidene fluoride trifluorethylene) as a ferroelectric layer and a cyanoethyl pullulan as an insulating buffer layer for the first time. The CEP thin films were deposited on Si substrate by using a sol-gel method. The coated P(VDF-TrFE) films on CEP/Si structure were crystallized. For the Au/P(VDF-TrFE)/CEP/Si structure, the capacitance-voltage characteristics showed hysteresis loops, the memory window width was about 4.6V at a bias sweep range of +/- 5V. The leakage current density was about 5.5 x 10(-7) A/cm(2) at 5V for the thick film from the 5 wt% solution.

본 논문에서는 종이를 기판으로 사용하고 용액공정이 가능한 강유전체 메모리 소자의 제작 가능성을 검토하였다. 유기물 강유전체인 "폴리비닐리덴트리플루오르에틸렌" 용액을 하부전극이 형성된 종이기판 위에 스핀코핑 방법을 이용하여 도포하였다. 하부전극으로는 진공증착법을 이용하여 알루미늄을 증착하였고, 도포된 "폴리비닐리덴트리플루오르에틸렌" 용액은 열처리 과정을 통해 결정화하였다. 제작된 "폴리비닐리덴트리플루오르에틸렌" 박막은 주사 전자 현미경법(SEM), 원자간력 현미경(AFM)을 이용하여 박막의 단면 및 표면의 특성을 평가하였다. 전압에 따른 분극특성 측정을 통해, 종이기판 위에 형성된 "폴리비닐리덴트리플루오르에틸렌" 박막이 매우 훌륭한 강유전체 특성을 보여주고 있음을 확인하였다. 또한, 종이기판의 응용가능성을 검토하기 위하여, 실리콘 기판위에 제작한 "폴리비닐리덴트리플루오르에틸렌" 박막과의 비교에 있어서도 손색없는 강유전체 특성을 보여주고 있음을 알 수 있었다. 이러한 결과들은 종이를 기판으로 이용하여 전자소자들을 제작 할 수 있음을 시사하며, 또한 용액공정으로 고밀도의 저렴한 강유전체 메모리 소자를 손쉽게 제작 할 수 있다는 것을 의미한다. In this study, It has been demonstrated a new and realizable possibility of the ferroelectric random access memory devices by all solution processing method with paper substrates. Organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin films were formed on paper substrate with Al electrode for the bottom gate structure using spin-coating technique. Then, they were subjected to annealing process for crystallization. The fabricated PVDF-TrFE thin films were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was found from polarization versus electric field (P-E) measurement that a PVDF-TrFE thin film on paper substrate showed very good ferroelectric property. This result agree well with that of a PVDF-TrFE thin film fabricated on the rigid Si substrate. It anticipated that these results will lead to the emergence of printable electron devices on paper. Furthermore, it could be fabricated by a solution processing method for ferroelectric random access memory device, which is reliable and very inexpensive, has a high density, and can be also fabricated easily.

A ferroelectric field-effect transistor on a cellulose paper for nonvolatile memory application is fabricated by a low-cost solution-based-only fabrication process. A ferroelectric material, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), is used to obtain a wide threshold voltage (V-TH) window of similar to 20V for the transistor on paper. An on/off current ratio of similar to 10(2) is also obtained with a semiconducting channel material, Poly(3-hexylthiophene) (P3HT).

The electrical and ferroelectric properties with different amounts of chemical bonding states at the polymer/metal interface were examined quantitatively in a ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) film sandwiched between the top and bottom electrodes on which the surface had been modified by rapid thermal processing in a N2 atmosphere. The capacitors with the heat-treated bottom electrodes at different temperatures showed a lower charge storing capacitance. Ultraviolet photoelectron spectroscopy showed that the capacitance enhancement and field shift to lower coercive value resulted from the relatively larger increase in anions (N,O) than cations (Ti) and the reduction of NC bonding in the reaction product (TiNxOy) on the surface of the bottom electrode, respectively.

Chemical force microscopy using probe tips subjected to liquid-phase chemical modification enables the study of intermolecular forces on a nanoscale, as well as imaging of the chemical inhomogeneity of a sample’s surface with high spatial resolution. However, in adhesive force measurements, the adhesive force between the tip and the sample could easily be affected by interactions caused by molecules in both the contact and the noncontact parts. A novel method involving local chemical modification of the tip is presented. The method is performed by adding a solution of a modification reagent in ethanol when the cleaned tip is approaching the substrate’s surface. The adhesive forces between the substrate’s surface and various types of tips were investigated using atomic force microscopy. This novel method could be helpful for increasing the resolution of chemical force microscopy and for measuring the contact area between the tip and the substrate’s surface.

Various surfaces have been used for deoxyribonucleic acid (DNA) immobilization, one example being a silanized surface. This is useful for determining DNA lengths and, thus, locating specific gene sequences in DNA by using fluorescence microscopy and scanning probe microscopy. In this study, we deposited DNA by using the molecular combing method and, we used fluorescence microscopy to study how the chain lengths of n-alkylsilanes affected the surface density of DNA deposited on the silanized surfaces in a tris-ethylenediaminetetraacetic acid (TE) buffer. The forces between a cleaned silicon-nitride (Si3N4) tip and each substrate surface in aqueous buffers at various pH levels (1.0 ~ 9.0) were also studied by using atomic force microscopy to measure the force-distance curves. We explain why the density of lambda bacteriophage DNA (λ-DNA) deposited by using the molecular combing method at pH 8 was lower on the silanized surface with the shorter alkyl chain than it was on the silanized surface with the longer alkyl chain in terms of the electrical double layer (EDL) and the adhesive force.

Precursor films based on poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and P(VDF-TrFE) blended with Pb(Zr,Ti)O3 were spin-coated on Si-substrates and subsequently annealed at 170°C. X-ray diffraction studies showed that the amorphous precursor films crystallize to the γ-phase P(VDF-TrFE) without involving the formation of other polymorphs when the P(VDF-TrFE) is blended with Pb(Zr,Ti)O3, resulting in phase mixtures composed of a crystalline γ-phase P(VDF-TrFE) and an amorphous Pb(Zr,Ti)O3. A larger memory window width and higher accumulation capacitance, as well as a lower leakage current density are induced by the blended Pb(Zr,Ti)O3 within the low operating voltage ranges from −3.0 to 3.0V and from −2.0 to 2.0V for 20wt% and 40wt% Pb(Zr,Ti)O3 blending, respectively. These improvements not only in the hysteretic capacitance–voltage characteristics but also in the leakage current density–electric field are directly correlated with the phase mixtures, their volume fraction, dipole moments, and formation of interface layer between the blended film and Si substrate.

Precursor films based on poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and P(VDF-TrFE) blended with Pb(Zr,Ti)O3 were deposited on Si (100) substrates by spin-coating, and subsequently annealed at 443 K for 0.5 h. These films were then characterized using X-ray diffraction, atomic force microscopy and capacitance-voltage curves. Blending the precursor films of Pb(Zr,Ti)O3 with P(VDF-TrFE) led to the formation of an amorphous oxide whose concentration was proportional to the Pb(Zr,Ti)O3 content. This resulted in extension of the memory-window width with a large voltage difference ranging from 0.07 V to 4.5 V for metal-ferroelectric-silicon capacitors. Moreover, the formation of the amorphous oxide resulted in parallel shifts toward positive or negative voltages in the capacitance-voltage curves because of the fixed negative or positive charge of the oxide at the ferroelectric/Si-substrate interface. These tunable ferroelectric properties open up possibilities for diverse applications and are essential for functional devices, as well as for the commercialization of nonvolatile high-density FeRAM devices.

We propose a new particle-insertion method for a reflective display based on the structure of a quick response-liquid powder display (QR-LPD). To compare this method with the reported simple loading method, two panels are fabricated in the same panel condition of which the width of ribs is 30 μm, the cell size is 220 μm 220 μm, the cell gap is 116-120 μm, the m value of the black particles is μC/g and that for the white particles is μC/g. This method excludes the non-moving particles, inserting only mobile particles into a substrate by using electric fields so that a panel fabricated by the particle-moving method can drive most of the particles in a cell. Also, most of the particles move at the threshold voltage of 40 V with enhanced reflectivity.