共查询到20条相似文献,搜索用时 31 毫秒
1.
《Organic Electronics》2007,8(4):415-422
Large positive shifts of turn-on voltage Vto were observed in ferroelectric organic thin film transistor using P(VDF-TrFE) copolymer (57–43 mol%) as gate insulator during OFF to ON state sweeping. The shift of the transfer characteristic up to +25 V is attributed to the accumulation of mobile charge carriers (holes) in pentacene layer even during the device OFF state. The observed phenomena were first discussed on the basis of a negative surface potential created by the dipole field of a polar dielectric and trap states in an organic semiconductor layer. It was however found that these were unable to fully address the observed strong Vto shift due to the presence of large polarization in the P(VDF-TrFE) layer. A mechanism of negative polarization-compensating charges which are injected to the insulator region next to the semiconductor layer was proposed and examined to understand the phenomenon. The turn-on voltage is found to change with different magnitude of positive voltage pulses, and corresponds to different amount of charges injected for compensation. Time measurement of drain current shows a transient decaying behavior when gate bias is switched from positive to negative polarity which confirms the trapping of negative charges in the insulator. 相似文献
2.
Pengfei Hou Cheng Chen Bo Li Shuaizhi Zheng Jinbin Wang Xiangli Zhong Min Liao 《Advanced functional materials》2021,31(19):2011029
Ferroelectric materials feature a switchable spontaneous electric polarization and can enable low-power logic and nonvolatile memories. These applications require reliable and precise control of ferroelectric domains and domain walls in ferroelectric thin films. Mechanical manipulation is a promising route to engineer ferroelectric domains, but it has proved ineffective when going beyond a critical thickness. Here, multi-step 90° switching polarization reversal processes in (111)-oriented PbZr0.2Ti0.8O3 thin films by applying mechanical forces along the direction parallel to the domain bands are reported. By probing the interrelationships between the relevant order parameters, coupled lattice distortion and piezoelectricity is revealed to facilitate domain switching from downward to upward in PbZr0.2Ti0.8O3, a mechanism that is supported by the evolution of domains and electrical performances at different temperatures and under varying pressures, respectively. The multi-step domain reversal processes render PbZr0.2Ti0.8O3 thin films an excellent candidate for multilevel data storage. The study's results have implications for the manipulation of polarization switching in ferroelectrics and open an avenue to domain reversal driven by mechanical loads for the development of next-generation ferroelectric devices. 相似文献
3.
《Organic Electronics》2014,15(1):22-28
We report the charge injection characteristics in poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), as a function of electrode material in metal/ferroelectric/metal device structures. Symmetric and asymmetric devices with Al, Ag, Au and Pt electrodes were fabricated to determine the dominant carrier type, injection current density, and to propose transport mechanisms in the ferroelectric polymer. Higher work function metals such as Pt are found to inject less charges compared to lower work function metals, implying n-type conduction behavior for P(VDF-TrFE) with electrons as the dominant injected carrier. Two distinct charge transport regimes were identified in the P(VDF-TrFE) devices; a Schottky-limited conduction regime for low to intermediate fields (E < 20 MV/m), and a space-charge limited conduction (SCLC) regime for high fields (20 < E < 120 MV/m). Implication of these results for degradation in P(VDF-TrFE) memory performance are discussed. 相似文献
4.
Jiyoon Kim Jongin Hong Moonkyu Park Wu Zhe Dongjin Kim Yu Jin Jang Dong Ha Kim Kwangsoo No 《Advanced functional materials》2011,21(22):4277-4284
A facile route is presented for the fabrication of spherical PbTiO3 (PTO) nanodot arrays on platinized silicon substrates using PbO vapor phase reaction sputtering on micellar monolayer films of polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) loaded with TiO2 sol–gel precursor. Short exposure to PbO transforms the amorphous TiO2 into polycrystalline PTO, while keeping the inherent size and periodicity of TiO2 nanodots. HRTEM images show that the spherical PTO nanodots, with an average size and height of 63 nm and 40 nm, respectively, are fixed on the Pt supported by residual carbon. XPS narrow scan spectra of Ti 2p and O 1s strongly verify the evolution of chemical identity and the reduction of the Ti‐O binding energy from TiO2 to PTO. The amplitude and phase images of piezoelectric force microscopy (PFM) confirm a multidomain structure attributed by the crystalline orientation of the PTO nanodots. Furthermore, the discrete PTO nanodots show remarkable switching properties due to the low strain field induced by the small lateral size, and the absence of domain pinning effects by grain boundary. 相似文献
5.
Phase-pure multiferroic BiFeO3 (BFO) was prepared by the coprecipitation technique using diverse precursors bismuth oxide at temperature as low as 400°C. The dependence of structural, microstructural, thermal, electrical (AC and DC), and magnetic properties on sintering temperature was systematically investigated. Uniaxially pressed samples (Ø8 mm) were sintered in air at 500°C to 800°C for 4 h. X-ray diffraction analysis was used to determine the amorphous and perovskite nature of as-synthesized and calcined/sintered samples, respectively. The crystallite size of sintered powders increased from 47 nm to 67 nm. Scanning electron microscopy showed grain growth during sintering, which improved intergranular connectivity and decreased porosity in the samples. The ferroelectric to paraelectric Curie transition temperature (T C) of pure BFO powder was detected by differential scanning calorimetry analysis and found to be 820°C ± 1°C. The samples exhibited high AC resistivity and dielectric constant, and low loss tangent values. The samples exhibited weak ferromagnetic behavior with an unsaturated magnetization versus magnetic field hysteresis loop at room temperature. Ferroelectric behavior and variation in remnant polarization and coercivity were observed from polarization versus electric field loops. Enhanced capacitance in the magnetic field revealed the magnetoelectric effect in the samples. 相似文献
6.
Sol Lee Nam Khanh Nguyen Wonkyo Kim Minje Kim Viet Anh Cao Junghyo Nah 《Advanced functional materials》2023,33(43):2307588
Extensive utilization of electronic devices and wireless equipment require human to take affirmative measures to weaken unwanted electromagnetic wave radiations. Herein, a ferroelectric poly[(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)-MXene]-poly(3,4-ethylenedioxythiophene) (PEDOT) multilayered film is developed that can increase electromagnetic interference (EMI) shielding performance through electrical polarization. The MXene is encapsulated by a P(VDF-TrFE) matrix, which inhibits oxidation, and a highly conductive MXene is created conductive network resulting in enhancement EMI shielding effectiveness (EMI SE). Furthermore, the surface pattern inducing multiple scattering and PEDOT layer contributes to the increasing absorption due to the electrically conductive PEDOT. Thanks to the electrically polarized and negatively charged P(VDF-TrFE)-MXene, the composite film demonstrates superior EMI SE and absolute EMI SE (SSEt) are exhibited remarkable ≈61 dB and 15230 dB cm2g−1 with high absorptivity (0.87) at thickness of 120 µm in X-band. Additionally, P(VDF-TrFE)-MXene composite film is applicable to motion and thermo-resistive sensor due to the negatively charged P(VDF-TrFE) and thermo-resistive property of PEDOT, respectively, for multifunctionality. This work provides a feasible avenue for flexible absorption dominant EMI shielding materials via electrical polarization with remarkable EMI shielding performance. 相似文献
7.
Jian-Min Yan Jing-Shi Ying Ming-Yuan Yan Zhao-Cai Wang Shuang-Shuang Li Ting-Wei Chen Guan-Yin Gao Fuyou Liao Hao-Su Luo Tao Zhang Yang Chai Ren-Kui Zheng 《Advanced functional materials》2021,31(40):2103982
Information processing with optoelectronic devices provides an alternative way to efficiently process hybrid optical and electronic signals. Ferroelectric field-effect transistors (FeFETs) can effectively respond to external optical and electrical stimuli by modulating their polarization states. Here, a 2D FeFET is demonstrated by the epitaxial growth of high-quality 2D bismuth layered oxyselenide (Bi2O2Se) films on PMN-PT(001) ferroelectric single-crystal substrates. Upon switching the polarization direction of PMN-PT, the authors realize in situ, reversible, and nonvolatile manipulation of the resistance of Bi2O2Se thin film ( ≈ 877%). The device simultaneously exhibits a polarization-dependent photoresponse through visible light (λ = 405 nm) and infrared light (IR, λ = 980 nm) illumination. Combining optical stimuli with ferroelectric gating, it is demonstrated that the devices not only show nonvolatile memory and optoelectronic responses, but also show coincidence detection of visible and IR light. This work holds great potential in constructing new multiresponse and multifunction 2D-FeFETs. 相似文献
8.
Xiang‐Zhong Chen Qian Li Xin Chen Xu Guo Hai‐Xiong Ge Yun Liu Qun‐Dong Shen 《Advanced functional materials》2013,23(24):3124-3129
Ferroelectric vinylidene fluoride‐trifluoroethylene copolymer [P(VDF‐TrFE)] free‐standing ultrahigh density (≈75 Gb inch?2) nanodot arrays are successfully fabricated through a facile, high‐throughput, and cost‐effective nano‐imprinting method using disposable anodic aluminum oxide with orderly arranged nanometer‐scale pores as molds. The nanodots show a large‐area smooth surface morphology, and the piezoresponse in each nanodot is strong and uniform. The preferred orientation of the copolymer chains in the nanodot arrays is favorable for polarization switching of single nanodots. The ferroelectric polymer memory prototype can be operated by a few volts with high writing/erasing speed, which comply with the requirements of integrated circuit. This approach provides a way of directly writing nanometer electronic features in two dimensions by piezoresponse force microscopy probe based technology, which is attractive for high density data storage. 相似文献
9.
《Organic Electronics》2014,15(3):751-757
Effects of surface roughness as well as crystallinity onto functionalities of crystalline copolymer films were studied using a dipping method to inject the crystalline grains into voids among crystalline nano-rods. Differently from a widely-used fabrication method such as spin-coating of solution, we achieved a smooth surface and high crystallinity in ferroelectric P(VDF-TrFE) films, simultaneously. Varying dipping temperature and time, remnant polarization and relative dielectric constant values increased by 20% and 75% with a decrease of surface roughness from 20 nm to 7 nm in root mean square value, respectively. The ferroelectric stabilities of P(VDF-TrFE) film capacitors were found to be strongly dependent on the crystallinity. 相似文献
10.
Hybrid Improper Ferroelectricity in Multiferroic Superlattices: Finite‐Temperature Properties and Electric‐Field‐Driven Switching of Polarization and Magnetization
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Bin Xu Dawei Wang Hong Jian Zhao Jorge Íñiguez Xiang Ming Chen Laurent Bellaiche 《Advanced functional materials》2015,25(24):3626-3633
The so‐called hybrid improper ferroelectricity (HIF) mechanism allows to create an electrical polarization by assembling two nonpolar materials within a superlattice. It may also lead to the control of the magnetization by an electric field when these two nonpolar materials are magnetic in nature, which is promising for the design of novel magneto‐electric devices. However, several issues of fundamental and technological importance are presently unknown in these hybrid improper ferroelectrics. Examples include the behaviors of its polarization and dielectric response with temperature, and the paths to switch both the polarization and magnetization under electric fields. Here, an effective Hamiltonian scheme is used to study the multiferroic properties of the model superlattice (BiFeO3)1/(NdFeO3)1. Along with the development of a novel Landau‐type potential, this approach allows to answer and understand all the aforementioned issues at both microscopic and macroscopic levels. In particular, the polarization and dielectric response are both found to adopt temperature dependences, close to the phase transition, that agree with the behavior expected for first‐order improper ferroelectrics. And most importantly, a five‐state path resulting in the switching of polarization and magnetization under an electric field, via the reversal of antiphase octahedral tiltings, is also identified. 相似文献
11.
June-O Song Hun Kang I.T. Ferguson Sung-Pyo Jung H.P. Lee Hyun-Gi Hong Takhee Lee Tae-Yeon Seong 《Solid-state electronics》2005,49(12):990
We report on the improvement of the electrical characteristics of GaN-based light-emitting diodes (LEDs) fabricated with Ag (1 nm)/indium tin oxide (ITO) (250 nm) p-type contacts by using Ni nanodots. As-deposited Ag/ITO contacts with and without the Ni nanodots give non-linear electrical behaviour. However, annealing the samples at 530–630 °C for 1 min in air results in ohmic behaviour. The reverse leakage current characteristics of near UV LEDs are much improved when the Ni nanodots are used. The output power (at 20 mA) of LEDs fabricated with the Ni nanodots is enhanced by a factor of 1.34 as compared with that of LEDs made without the Ni nanodots. 相似文献
12.
Jingfeng Song Shihao Zhuang Michael Martin Luis A. Ortiz-Flores Binod Paudel Dmitry Yarotski Jiamian Hu Aiping Chen Bryan D. Huey 《Advanced functional materials》2021,31(34):2102311
Self-assembled BiFeO3-CoFe2O4 (BFO-CFO) vertically aligned nanocomposites are promising for logic, memory, and multiferroic applications, primarily due to the tunability enabled by strain engineering at the prodigious epitaxial vertical interfaces. However, local investigations directly revealing functional properties in the vicinity of such critical interfaces are often hampered by the size, geometry, microstructure, and concomitant experimental artifacts. Ferroelectric switching in the presence of lateral distributions of vertical strain thus remains relatively unexplored, with broader implications for all strain-engineered functional devices. By implementing tomographic atomic force microscopy, 3D domain orientation mapping, and spatially-resolved ferroelectric switching movies, local tensile strain significantly impacts the ferroelectric switching, principally by retarding domain nucleation in the BFO nearest to the vertically epitaxial tensile-strained interfaces. The relaxed centers of the BFO pillars become preferred domain nucleation and growth sites for low biases, with up to an order of magnitude change in the edge:center switching ratio for high biases. The new, multi-dimensional imaging approach—and its corresponding insights especially for directly strained interface effects on local properties—thereby advances the fundamental understanding of polarization switching and provides design principles for optimizing functional response in confined nanoferroic systems. 相似文献
13.
Nina Balke Martin Gajek Alexander K. Tagantsev Lane W. Martin Ying‐Hao Chu Ramamoorthy Ramesh Sergei V. Kalinin 《Advanced functional materials》2010,20(20):3466-3475
Ferroelectric polarization switching in epitaxial (110) BiFeO3 films is studied using piezoresponse force microscopy of a model in‐plane capacitor structure. The electrode orientation is chosen such that only two active domain variants exist. Studies of the kinetics of domain evolution allows clear visualization of nucleation sites, as well as forward and lateral growth stages of domain formation. It is found that the location of the reverse‐domain nucleation is correlated with the direction of switching in a way that the polarization in the domains nucleated at an electrode is always directed away from it. The role of interface charge injection and surface screening charge on switching mechanisms is explored, and the nucleation is shown to be controllable by the bias history of the sample. Finally, the manipulation of domain nucleation through domain structure engineering is illustrated. These studies pave the way for the engineering and design of the ferroelectric device structures through control of individual steps of the switching process. 相似文献
14.
Kang-Jun Baeg Soon-Won Jung Dongyoon Khim Juhwan Kim Dong-Yu Kim Jae Bon Koo Jordan R. Quinn Antonio Facchetti In-Kyu You Yong-Young Noh 《Organic Electronics》2013,14(5):1407-1418
We report the development of high-performance inkjet-printed organic field-effect transistors (OFETs) and complementary circuits using high-k polymer dielectric blends comprising poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) and poly(methyl methacrylate) (PMMA) for high-speed and low-voltage operation. Inkjet-printed p-type polymer semiconductors containing alkyl-substituted thienylenevinylene (TV) and dodecylthiophene (PC12TV12T) and n-type P(NDI2OD-T2) OFETs showed high field-effect mobilities of 0.1–0.4 cm2 V?1 s?1 and low threshold voltages down to 5 V. These OFET properties were modified by changing the blend ratio of P(VDF-TrFE) and PMMA. The optimum blend – a 7:3 wt% mixture of P(VDF-TrFE) and PMMA – was successfully used to realize high-performance complementary inverters and ring oscillators (ROs). The complementary ROs operated at a supplied bias (VDD) of 5 V and showed an oscillation frequency (fosc) as high as ~80 kHz at VDD = 30 V. Furthermore, the fosc of the complementary ROs was significantly affected by a variety of fundamental parameters such as the electron and hole mobilities, channel width and length, capacitance of the gate dielectrics, VDD, and the overlap capacitance in the circuit configuration. 相似文献
15.
Jiang-Rong Fang Xiao-Ya Luo Zhen Ma Zhen-Kui Shen Qian Lu Bing-Rui Lu Guo-Dong Zhu Xin-Ping Qu Ran Liu Yi-Fang Chen 《Microelectronic Engineering》2010,87(5-8):890-892
Poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), copolymer films nanostructures are attracting increasing interests for potential applications in FERAM, NEMS and sensors. In this work we apply hot embossing lithography to fabricate P(VDF-TrFE) copolymer nanostructures and investigate the influence of this patterning process on the material and electrical properties by using AFM, XRD, FTIR and Precision Ferroelectric Tester. It was found that nano-embossing technique offers not only a low-cost and effective way to fabricate nanoscale structures but also a way to control the orientation and crystal quality of P(VDF-TrFE) films. The electrical measurement also indicated superior ferroelectric characteristics for the imprinted structure to the un-imprinted area of P(VDF-TrFE) films. 相似文献
16.
17.
The electrical properties, memory switching behavior, and microstructures of ZrTiO4 thin films prepared by sol–gel method at different annealing temperatures were investigated. All films exhibited ZrTiO4 (111) and (101) orientations perpendicular to the substrate surface, and the grain size increased with increasing annealing temperature. A low leakage current density of 1.47×10?6 A/cm2 was obtained for the prepared films. The I–V characteristics of ZrTiO4 capacitors can be explained in terms of ohmic conduction in the low electric field region and Schottky emission in the high electric field region. An on/off ratio of 102 was measured in our glass/ITO/ZrTiO4/Pt structure with an annealing temperature of 600 °C. Considering the primary memory switching behavior of ZrTiO4, ReRAM based on ZrTiO4 shows promise for future nonvolatile memory applications. 相似文献
18.
Jubong ParkSeungjae Jung Joonmyoung LeeWootae Lee Seonghyun KimJungho Shin Hyunsang Hwang 《Microelectronic Engineering》2011,88(7):1136-1139
We investigated the resistive switching characteristics of Ir/TiOx/TiN structure with 50 nm active area. We successfully formed ultra-thin (4 nm) TiOx active layer using oxidation process of TiN BE, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) depth profiling. Compared to large area device (50 μm), which shows only ohmic behavior, 250 and 50 nm devices show very stable resistive switching characteristics. Due to the formation and rupture of oxygen vacancies induced conductive filament at Ir and TiOx interface, bipolar resistive switching was occurred. We obtained excellent switching endurance up to 106 times with 100 ns pulse and negligible degradation of each resistance state at 85 °C up to 104 s. 相似文献
19.
《Organic Electronics》2008,9(6):1087-1092
Poly(vinylidene fluoride-trifluoroethylene) (70–30 mol%) was used as the functional dielectric layer in organic ferroelectric field effect transistors (FeFET) for non-volatile memory applications. Thin P(VDF-TrFE) film samples spin-coated on metallized plastic substrates were stretch-annealed to attain a topographically flat-grain structure and greatly reduce the surface roughness and current leakage of semi-crystalline copolymer film, while enhancing the preferred β-phase of the ferroelectric films. Resultant ferroelectric properties (PR = |10| μC/cm2, EC = |50| MV/m) for samples simultaneously stretched (50–70% strain) and heated below the Curie transition (70 oC) were comparable to those resulting from high temperature annealing (>140 oC). The observed enhancements by heating and stretching were studied by vibration spectroscopy and showed mutual complementary effects of both processes. Organic FeFET fabricated by thermal evaporating pentacene on the smooth P(VDF-TrFE) films showed substantial improvement of semiconductor grain growth and enhanced electrical characteristics with promising non-volatile memory functionality. 相似文献
20.
Ferroelectric Pt/PZT/Pt capacitors with different PZT orientations are characterized before and after electrical fatigue. (111)c-oriented, tetragonal PZT is characterized by abrupt 180° switching and very high-quality hysteresis loops but is very prone to electrical fatigue, while the 90° switching which is dominant in unsaturated and/or unpoled (100)c PZT films results in slanted loops with low polarization but high endurance. 相似文献