共查询到20条相似文献,搜索用时 0 毫秒
1.
Ching-Lin Fan Yu-Zuo Lin Ping-Cheng Chiu Shea-Jue Wang Win-Der Lee 《Organic Electronics》2013,14(9):2228-2232
We demonstrate a bilayer passivation method using a Teflon and SiO2 combination layer to improve the electrical reliability of pentacene-based organic thin-film transistors (OTFTs). The Teflon was deposited as a buffer layer using a thermal evaporator that exhibited good compatibility with the underlying pentacene channel layer, and can effectively protect the OTFTs from plasma damage during the SiO2 deposition process, resulting in a negligible initial performance drop in OTFTs. Furthermore, because of the excellent moisture barrier ability of SiO2, the OTFTs exhibited good time-dependent electrical performance, even after 168 h of aging in ambient air with 60–80% relative humidity. 相似文献
2.
To improve the performances of pentacene-based organic thin-film transistors (OTFTs), a TPD buffer layer was inserted between the Au metal electrode and the pentacene channel layer. As shown by the ultraviolet photoelectron spectroscopy measurement, the Au work function was increased from 4.61 eV for Au in direct contact with pentacene to 4.74 eV and 4.78 eV for the sample inserted with 2-nm-thick and 3-nm-thick TPD buffer layers, respectively, between the Au metal electrode and the pentacene channel layer. Moreover, the contact resistance was reduced from 1 MΩ to 0.1 MΩ by inserting a 2-nm-thick TPD buffer layer. Compared with the transconductance of 2.67 × 10?7 S, the field-effect mobility of 0.46 cm2/V s, and the substhreshold swing of 1.78 V/decade for the conventional pentacene-based OTFTs without TPD buffer layer, the transconductance, the field-effect mobility, and the subthreshold swing were improved to 9.77 × 10?7 S, 1.68 cm2/V s, and 1.46 V/decade, respectively, for the pentacene-based OTFTs inserted with a 2-nm-thick TPD buffer layer. By considering the trade-off between the increase of Au work function and the tunneling effect, the optimal thickness of the TPD buffer layer in the pentacene-based OTFTs was 2 nm. 相似文献
3.
Ching-Lin Fan Yu-Zuo Lin Win-Der Lee Shea-Jue Wang Chao-Hung Huang 《Organic Electronics》2012,13(12):2924-2928
This study proposes an alternative planar bottom-contact (pBC) structure to enhance the electrical performance of pentacene-based organic thin-film transistors (OTFTs). This pBC structure uses a bilayer dielectric to control planarization with a precise etch depth and introduces a bilayer photoresist lift-off method to ensure that planarization produces an optimum flatness. Because of the improved growth continuity of pentacene near the edge of the source/drain electrodes, the contact resistance between the source/drain and the pentacene was reduced significantly, thereby enhancing the electrical performance of OTFTs. The mechanism for the enhanced performance was also verified by a physics-based numerical simulation. 相似文献
4.
This paper demonstrates non-volatile memory transistor using solution processable graphene oxide (GO) as charge storage nodes in the configuration, p++Si/SiO2/GO/Tunneling layer/Pentacene/Au. The tunneling layers are polymethylmethacrylate (PMMA) and polyvinylphenol (PVP). GO film could be deposited as single layered flakes with a uniform distribution using spin coating technique. The devices with PMMA as charge tunneling layer exhibited higher mobility and on/off ratio than PVP based devices. The devices show a large positive threshold voltage shift (∼24 V for PMMA and ∼15 V for PVP) from initial value during programming at gate voltage of +80 V kept for 10 s. The transfer curves can be restored approximately to its initial condition by applying an erasing voltage of −30 V for 10 s for both the devices. Since such a large shift is not observed without GO layer, we consider that memory effect was due to electron trapping in GO. Further, retention of the initial memory window was measured to be 63% and 37% after 3000 s for PMMA and PVP based devices, respectively. 相似文献
5.
Min-Kun Dai Jan-Tien Lian Tai-Yuan Lin Ming-Chung Chen Yian Tai Yang-Fang Chen 《Organic Electronics》2012,13(11):2229-2234
The influence of nematic liquid crystal molecules on the electrical properties and microstructure of polymer semiconductors poly(3-hexylthiophene) (P3HT) was investigated. It was found that the introduction of nematic liquid crystal molecules can significantly improve the performance of P3HT thin-film transistors, providing better electrical characteristics and enhanced mobility. The field-effect mobility of the device with liquid crystal modification can be enhanced by up to a factor of ten with respect to that of the pure P3HT device. UV–visible absorption spectroscopy, X-ray diffraction, and atomic force microscopy measurements show that the enhancement of charge-carrier mobility is achieved through a more highly organized morphology and a reduction in the density of traps presents in the P3HT/liquid crystal structure. The results shown here therefore illustrate a high-performance solution-processable thin-film transistors, which is quite feasible and can pave a key step for the practical applications of organic electronic devices. 相似文献
6.
Jaehoon Park Lee-Mi Do Jin-Hyuk Bae Ye-Sul Jeong Christopher Pearson Michael C. Petty 《Organic Electronics》2013,14(9):2101-2107
The electrical properties of top-contact pentacene thin-film transistors (TFTs) with a poly(methyl methacrylate) (PMMA) gate dielectric were analyzed in air and vacuum environments. Compared to the vacuum case, the pentacene TFT in air exhibited lower drain currents and more pronounced shifts in the threshold voltage upon reversal of the gate voltage sweep direction, together with a decrease in the field-effect mobility. These characteristic variations were explained in terms of two distinctive actions of polar H2O molecules in pentacene TFT. H2O molecules were suggested to diffuse under the source and drain contacts and interrupt the charge injection into the pentacene film, whereas those that permeate at the pentacene/PMMA interface retard hole depletion in and around the TFT channel. The diffusion process was much slower than the permeation process. The degraded TFT characteristics in air could be recovered mostly by storing the device under vacuum, which suggests that the air instability of TFTs is due mainly to the physical adsorption of H2O molecules within the pentacene film. 相似文献
7.
We report memory application for graphene as a floating gate in organic thin-film transistor (OTFT) structure. For graphene floating gate, we demonstrate a simpler synthesis method to form a discrete graphene layer by controlling the growth time during a conventional CVD process. The resulting organic memory transistor with the discrete graphene charge-storage layer is evaluated. The device was demonstrated based on solution-processed tunneling dielectric layers and evaporated pentacene organic semiconductor. The resulting devices exhibited programmable memory characteristics, including threshold voltage shifts (∼28 V) in the programmed/erased states when an appropriate gate voltage was applied. They also showed an estimated long data retention ability and program/erase cycles endurance more than 100 times with reliable non-volatile memory properties although operated without encapsulation and in an ambient condition. 相似文献
8.
The temperature-dependent electrical and charge transport characteristics of pentacene-based ambipolar thin-film transistors (TFTs) were investigated at temperatures ranging from 77 K to 300 K. At room temperature (RT), the pentacene-based TFTs exhibit balanced and high charge mobility with electron (μe) and hole (μh) mobilities, both at about 1.6 cm2/V s. However, at lower temperatures, higher switch-on voltage of n-channel operations, almost absent n-channel characteristics, and strong temperature dependence of μe indicated that electrons were more difficult to release from opposite-signed carriers than that of holes. We observed that μe and μh both followed an Arrhenius-type temperature dependence and exhibited two regimes with a transition temperature at approximately 210–230 K. At high temperatures, data were explained by a model in which charge transport was limited by a dual-carrier release and recombination process, which is an electric field-assisted thermal-activated procedure. At T < 210 K, the observed activation energy is in agreement with unipolar pentacene-based TFTs, suggesting a common multiple trapping and release process-dominated mechanism. Different temperature-induced characteristics between n- and p-channel operations are outlined, thereby providing important insights into the complexity of observing efficient electron transport in comparison with the hole of ambipolar TFTs. 相似文献
9.
Inserting a Mn-doped TiO2 layer for improving performance of pentacene organic thin-film transistors
Device performance of pentacene organic thin-film transistors (OTFTs) was significantly improved via inserting a Mn-doped TiO2 layer between pentacene semiconductor and the source–drain electrodes. In comparison with the OTFTs with only-Au electrodes, the introduction of a thin Mn-doped TiO2 layer leads to saturation current increasing from 31.9 μA to 0.22 mA, effective field-effect mobility improving from 0.24 to 1.13 cm2/V s, and threshold voltage downshifting from −11 to −2 V. These performance enhancements are ascribed to the significant reduction of contact resistance and smoothed surface of pentacene layer. This work may provide an effective approach to improve the performance of the pentacene based OTFTs by inserting a Mn-doped TiO2 layer. 相似文献
10.
Qijun SunSoonmin Seo 《Organic Electronics》2012,13(3):384-387
Organic zero drive load inverters based on pentacene thin film transistors with periodic groove patterned dielectrics are fabricated using nanoimprinting and soft-contact lamination methods. Depletion mode transistor behavior is achieved when the current direction is parallel to groove direction and enhancement mode transistor behavior is achieved when the directions are crossed. An organic inverter is created after connecting two soft-contact laminated transistors. The electrical performance of the drive transistor can be varied and the organic inverter is tunable. This is done by utilizing a PDMS stamp with the source-drain electrode and changing the angle between the current direction and groove direction. The gain and symmetry of the VTC is improved by using an enhancement mode transistor where the source-drain electrode formed by thermal evaporation instead of being a soft contact-laminated device. 相似文献
11.
The quality of the dielectric/organic semiconductor interface is a critical issue, because it determines the charge transport properties in organic thin-film transistors (OTFTs). High-k organic-inorganic hybrid films have received considerable attention for their outstanding dielectric properties, including low leakage currents, high breakdown fields, and suitable band offsets against the organic semiconductor. However, Hf and Zr hybrid gate dielectrics on p-type OTFTs show poor charge transport properties in the organic semiconductor channel, due to the polaron disorder elicited by the high-k properties and the presence of the –N(CH3)2 polarity (hole trapper) on the dielectric/semiconductor interface. In this report, the surface of the Hf and Zr hybrid dielectrics was capped by an ultra-thin poly-1,3,5-trivinyl-1,3,5,-trimethyl-cyclosiloxane (pV3D3) layer formed via an initiated chemical vapor deposition (iCVD) process, to modify the hybrid dielectrics/semiconductor interface. The pV3D3-capped Hf and Zr hybrid OTFTs show an enhanced VT stability while a large amount of VT shift was observed from the Hf and Zr hybrid OTFTs. This large amount of VT shift is attributed to the hole trap sites originated by –N(CH3)2 on the uncapped hybrid dielectrics. Furthermore, the p-type OTFTs with the pV3D3-capped hybrid dielectrics show a higher mobility than those with the uncapped hybrid dielectrics. The presence of the non-polar/low-k pV3D3 on the hybrids contribute to narrow the density of state (DOS) in the organic channel, improving the charge transport properties. This combined approach using the bulk layer of Hf and Zr hybrid films and the pV3D3 capping layer can overcome the limitations of single-layer hybrid dielectrics and improve the overall device performance of the OTFTs. 相似文献
12.
In this work, pentacene-based thin film phototransistors were fabricated with a photocurable polymer insulator and their electrical stability was monitored when the devices were exposed to light sources at different wavelengths. The magnitude of the photocurrent induced by illumination was found to be the result of two distinct factors: a direct photocurrent, related to electron–hole pair generation, and a current enhancement caused by a threshold voltage shift. The direction of threshold translation is attributed to the nature of trap states, specifically those located in the pentacene film near the interface with the polymer, and is affected by a measurement-induced effect, so that the photosensitivity can be modulated by a persistent gate bias during illumination. The equations for these two contributions were developed to study the light effects on material structure, the trapping process of electrons at the insulator–semiconductor interface and the photoconductive efficiency in the organic semiconductor. 相似文献
13.
《Organic Electronics》2014,15(5):991-996
High performance organic thin-film transistors (OTFTs) are fabricated on an epoxy based photo-patternable organic gate insulating layer (p-OGI) using a top contact thin-film transistor configuration. This negative tone p-OGI material is composed of an epoxy type polymer resin, a polymeric epoxy cross-linker, and a sulfonium photoacid generator (PAG). Features from p-OGI can be precisely patterned down to ∼3 μm via i-line photolithography. In order to evaluate the potential of this epoxy type resin as a gate insulator, we evaluated the dielectric properties of the p-OGI and its gate insulating performance upon fabricating solution processed OTFTs using an organic semiconductor (OSC), namely tetrathienoacene-DPP copolymer (PTDPPTFT4). Results show that the PTDPPTFT4 based OTFTs with this p-OGI exhibit field-effect mobilities up to 1 cm2 V−1 s−1, indicating the potential of high performance solution processed OTFT based on an epoxy based p-OGI/OSC system. 相似文献
14.
15.
Improve on/off ratio of organic heterojunction transistors by adopting single-sandwich configuration
Jianwu Shi Hua Wang Haibo Wang Hongkun Tian Yanhou Geng Donghang Yan 《Solid-state electronics》2011,61(1):65-68
Organic heterojunction transistors (OHJTs) based on 5,5′″-bis(naphtha-2-yl)-2,2′:5″,2′″-quaterthiophene (NaT4)/copper-hexadecafluoro-phthalocyanine (F16CuPc) heterojunction were fabricated in single-sandwich and sandwich configurations, respectively. All the devices operated in depletion-accumulation (normally-on) mode. High field-effect mobility of 0.35 cm2/Vs was obtained for all devices, which was higher than that, 0.20 cm2/Vs of the devices with NaT4 as active layer. The on/off ratio of 1 × 105 was obtained for OHJTs with single-sandwich configuration, which is three orders of magnitude higher than that of OHJTs with sandwich configuration. Compared with OHJTs with sandwich configuration, the higher on/off ratio was mainly determined by the lower off state current in OHJTs with single-sandwich configuration. In OHJTs with single-sandwich configuration, the well-type shield effect of the source and drain electrodes caused a very narrow empty region in F16CuPc film, which is responsible for the lower off state current. 相似文献
16.
掺氮ZnO薄膜的光电特性及其薄膜晶体管研究 总被引:6,自引:5,他引:1
Using NH3 as nitrogen source gas, N-doped ZnO (ZnO:N) thin films in c-axis orientation were deposited on glass substrates by radio frequency magnetron sputtering at room temperature. The ZnO:N thin films display significant increase of resistivity and decrease of photoluminescence intensity. As-grown ZnO:N material was used as active channel layer and Si3N4 was used as gate insulator to fabricate thin-film transistor. The fabricated devices on glasses demonstrate typical field effect transistor characteristics. 相似文献
17.
Zhu Xiaming Wu Huizhen Wang Shuangjiang Zhang Yingying Cai Chunfeng Si Jianxiao Yuan Zijian Du Xiaoyang Dong Shurong 《半导体学报》2009,30(3):033001-033001-4
Using NH3 as nitrogen source gas, N-doped ZnO (ZnO:N) thin films in c-axis orientation were deposited on glass substrates by radio frequency magnetron sputtering at room temperature. The ZnO:N thin films display significant increase of resistivity and decrease of photoluminescence intensity. As-grown ZnO:N material was used as active channel layer and Si3N4 was used as gate insulator to fabricate thin-film transistor. The fabricated devices on glasses demonstrate typical field effect transistor characteristics. 相似文献
18.
The modification of printed silver electrode surfaces for use as the bottom-contact electrodes of organic thin-film transistors (OTFTs) is reported. Printed silver electrodes fabricated using the surface photoreactive nanometal printing (SuPR-NaP) technique are inevitably covered with an inert surface layer of alkylamines that is originally used for encapsulation of the silver nanoparticles (AgNPs). However, it may act as a built-in protective layer against carrier injections. We demonstrate that a simple vapor exposure method is sufficient for converting the protective layer into a layer that assists carrier injection. As modifiers, we used various types of fluorinated benzenethiols that exhibit a stronger coordination with the silver surfaces than the alkylamimes. We detected the chemical conversion from alkylamine encapsulation to thiol coordination by surface enhanced Raman spectroscopy (SERS) and evaluated the improvement in the carrier injection using a transfer length method (TLM) for the OTFTs. Among the modifiers, the pentafluorobenzenethiol (PFBT) treatment significantly improves the device performance and stability of the OTFTs. 相似文献
19.
Jin Sun Jung Eun Hei Cho Soyoung Jo Kyung Hwan Kim Dong Hoon Choi Jinsoo Joo 《Organic Electronics》2013,14(9):2204-2209
We fabricated organic thin film transistors (OTFTs) using soluble 5,5′-(2,6-Bis((4-hexylphenyl)ethynyl)anthracene-9,10-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthieno[3,2-b]thiophene (HTT-ant-THB) as an active layer. We studied the photo-responsive and the gate field-dependent charge transport characteristics of the HTT-ant-THB-based OTFTs. When light (λex = 505 nm) was irradiated on the OTFTs, negative differential resistance (NDR) behavior (i.e., negative slope of the current versus voltage curve) was observed in the reverse bias region of the source-drain current versus voltage characteristics. The NDR effect observed in this study is unique and is controlled by the wavelength and power of the incident light. The current hysteresis and NDR characteristics can be explained in terms of the trapping and releasing mechanism of the mobile charges at the interface between the electrodes and the organic layer. In addition, the NDR effect in the device disappeared on applying negative gate bias. 相似文献