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1.
Jaya Lohani Manoj Gaur Upendra Kumar V. R. Balakrishnan Harsh S. V. Eswaran 《中国物理快报》2010,27(4):234-237
In order to conduct electrical studies on organic thin film transistors, top-contact devices are fabricated by growing polycrystalline films of freshly synthesized pentacene over Si/SiO2 substrates with two different channel widths under identical conditions. Reasonable field effect mobilities in order of 10^-2-10^-3 cm^2V^-1s^-1 are obtained in these devices. An elaborative electrical characterization of all the devices is undertaken to study the variance in output saturation current, field effect mobility, and leakage current with aging under ambient conditions. As compared to the devices with longer channel width, the devices with shorter channel width exhibit better electrical performance initially. However, the former devices sustain the moderate performance much longer than the latter ones. 相似文献
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Organic Light-Emitting Diodes with Magnesium Doped CuPc as an Efficient Electron Injection Layer 下载免费PDF全文
Bright organic electroluminescent devices are developed using a metal-doped organic layer intervening between the cathode and the emitting layer. The typical device structure is a glass substrate/indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/N,N'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB)/Tris(8-quinolinolato) aluminum(Alq3)/Mg-doped CuPc/Ag. At a driving voltage of 11 V, the device with a layer of Mg-doped CuPc (1:2 in weight) shows a brightness of 4312cd/m^2 and a current efficiency of 2.52cd/A, while the reference device exhibits 514 cd/m^2 and 1.25 cd/A. 相似文献
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Performance Improvement of Organic Thin Film Transistors Based on Gate Insulator Polymethyl-Methacrylate-co-Glyciclyl-Methacrylate 下载免费PDF全文
Organic thin transistors (OTFTs) on indium tin oxide glass substrates are prepared with polymethyl-methacrylate-co-glyciclyl-methacrylate (PMMA-GMA) as the gate insulator layer and copper phthalocyanine as the organic semiconductor layer. By controlling the thickness, the average roughness of surface is reduced and the OTFT performance is improved with leak current decreasing to 10^-11 A and on/off ratio of 10^4. Under the condition of drain-source voltage -20 V, a threshold voltage of -3.5 V is obtained. The experimental results show that PMMA-GMA is a promising insulator material with a dielectric constant in a range of 3.9-5.0. 相似文献
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Atomic Diffusion in Cu/Si (111) and Cu/SiO2/Si (111) Systems by Neutral Cluster Beam Deposition 下载免费PDF全文
The Cu films are deposited on two kinds of p-type Si (111) substrates by ionized duster beam (ICB) technique. The interface reaction and atomic diffusion of Cu/Si (111) and Cu/SiO2/Si (111) systems are studied at different annealing temperatures by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results are obtained: For the Cu/Si (111) samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230℃. The diffusion coefficients of the samples annealed at 230℃ and 500℃ are 8.5 ×10^-15 cm^2.s^-1 and 3.0 ×10^-14 cm^2.s^-1, respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2//Si (111) samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450℃. The diffusion coefficients of Cu in Si are calculated to be 6.0 ×10^-16 cm^2.s^-1 at 450℃, due to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si. 相似文献
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Electrical Characterization of Copper Phthalocyanine Thin-Film Transistors with Fluoride Gate Insulator 下载免费PDF全文
Different fluoride materlals are used as gate dielectrics to fabricate copper phthalocyanine (CuPc) thin film transistors (OTFTs). The fabricated devices exhibit good electrical characteristics and the mobility is found to be dependent on the gate voltage from 10^-3 to 10^-1 cm^2V^-1 s^-1. The observed noticeable electron injection at the drain electrode is of great significance in achieving ambipolar OTFTs, The same method for formation of organic semiconductors and gate dielectric films greatly simplifies the fabrication process. This provides a convenient way to produce high-performance OTFTs on a large scale and should be useful for integration in organic displays. 相似文献
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桑立雯 ;秦志新 ;岑龙斌 ;沈波 ;张国义 ;李书平 ;陈航洋 ;刘达艺 ;康俊勇 ;成彩晶 ;赵鸿燕 ;鲁正雄 ;丁嘉欣 ;赵岚 ;司俊杰 ;孙维国 《中国物理快报》2008,25(1):258-261
We report AlGaN-based back-illuminated solar-blind Schottky-type ultraviolet photodetectors with the cutoff- wavelength from 280nm to 292nm without bias. The devices show low dark current of 2.1× 10^-6A/cm^2 at the reverse bias of 5 V. The specific detectivity D* is estimated to be 3.3 × 10^12cmHz^1/2 W^-1 . To guarantee the performance of the photodetectors, the optimization of AlGaN growth and annealing condition for Schottky contacts were performed. The results show that high-temperature annealing method for Ni/Pt Schottky contacts is effective for the reduction of leakage current. 相似文献
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Seokgeun Jin Byung Jun Jung Chung Kun Song Jeonghun Kwak 《Current Applied Physics》2014,14(12):1809-1812
We introduce a room temperature and solution-processible vanadium oxide (VOx) buffer layer beneath Au source/drain electrodes for bottom-contact (BC) organic field-effect transistors (OFETs). The OFETs with the VOx buffer layer exhibited higher mobility and lower threshold voltages than the devices without a buffer layer. The hole mobility with VOx was over 0.11 cm2/V with the BC geometry with a short channel length (10 μm), even without a surface treatment on SiO2. The channel width normalized contact resistance was decreased from 98 kΩ cm to 23 kΩ cm with VOx. The improved mobility and the reduced contact resistance were attributed to the enhanced continuity of pentacene grains, and the increased work function and adhesion of the Au electrodes using the VOx buffer layer. 相似文献
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Synthesis,Characterization of 9, 9'-Bianthracene and Fabrication of 9, 9'-Bianthracene Field-Effect Transistors 下载免费PDF全文
We synthesize and purify 9, 9'-bianthracene with the purity up to 96.4%. The electronic and crystallographic structures of 9, 9'-bianthracene are studied. The results of a joint experimental investigation based on a combination of x-ray diffraction (XRD) spectra, hydrogen nuclear magnetic (HNMR) spectra, infrared absorption (FT-IR) spectra, and mass spectra (MS) of 9, 9'-bianthracene are obtained. The uniform compact film is observed by an atomic-force microscope (AFM). Organic field effect transistors (OFETs) with an active layer based on the synthesized 9, 9'-bianthracene are fabricated for the first time. Its field-effect mobility is as large as 0.067 cm^2 /(V·s) and the on/off ratio is above 5 ×10^4. The result demonstrates that the oligomerization of a small semiconductor molecule is an effective method to develop high-mobility organic semiconductors. 相似文献
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采用EuF3薄层修饰低功函数金属Ag源、漏电极,制备了CuPc有机场效应晶体管,研究了不同厚度EuF3对器件性能的影响。结果表明,EuF3的厚度由0 nm增至0.6 nm时,接触电阻由23.65×105 Ω·cm减 至3.86×105 Ω·cm,使得器件载流子迁移率由1.5×10-3 cm2·V-1·s-1提高到4.65×10-3 cm2·V-1·s-1。 UPS测试结果表明,薄层EuF3在Ag与有机半导体间形成了界面偶极势垒,使源漏电极表面功函数增大,空穴注入势垒降低,Ag电极与有机半导体层界面的接触电阻减小,进而提升了空穴的注入效率。 相似文献
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Influence of Vacuum Organic Contaminations on Laser-Induced Damage of 1064 nm Anti-Reflective Coatings 下载免费PDF全文
We investigate the influence of vacuum organic contaminations on laser-induced damage threshold (LIDT) of optical coatings. Anti-reflective (AIR) coatings at 1064 nm made by Ta2 O5/SiO2 are deposited by the ion beam sputtering method. The LIDTs of AR coatings are measured in vacuum and in atmosphere, respectively. It is exhibited that contaminations in vacuum are easily to be absorbed onto optical surface because of lower pressure, and they become origins of damage, resulting in the decrease of LIDT from 24.5J/cm^2 in air to 15.TJ/cm^2 in vacuum. The LIDT of coatings in vacuum has is slightly changed compared with the value in atmosphere after the organic contaminations are wiped off. These results indicate that organic contaminations are the main reason of the LIDT decrease in vacuum. Additionally, damage morphologies have distinct changes from vacuum to atmosphere because of the differences between the residual stress and thermal decomposability of filmy materials. 相似文献
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Enhanced Green Electrophosphorescence from Oxadiazole-Functionalized Iridium Complex-Doped Devices Using Poly(9,9-Dioctylfluorene) Instead of Poly(N-Vinylcarbazole) as a Host Matrix 下载免费PDF全文
Optoelectronic properties of the oxadiazole-functionalized iridium complex-doped polymer light-emitting devices (PLEDs) are demonstrated with two different polymeric host matrices at the dopant concentrations 1-8%. The devices using a blend of poly(9,9-dioctylttuorene)(PFO) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) as a host matrix exhibited a maximum luminance efficiency of 11.3 cd/A at 17. 6 mA/cm^2. In contrast, the devices using a blend of poly(N-vinylcarbazole) (PVK) and PBD as a host matrix reveal only a peak luminance efficiency of 6.Scd/A at 4.1 mA/cm^2. The significantly enhanced electrophosphorescent emissions are observed in the devices with the PFO-PBD blend as a host matrix. This indicates that choice of polymers in the host matrices is crucial to achieve highly efficient phosphorescent dye-doped PLEDs. 相似文献
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选用五氧化二钽(Ta2O5)-聚甲基丙烯酸甲酯(PMMA)复合材料作为栅绝缘层制备了并五苯有机场效应晶体管(OFETs)。通过在Ta2O5表面旋涂一层PMMA可以降低栅绝缘层的表面粗糙度,增大其场效应晶体管的迁移率。研究了厚度在20~60 nm范围内的PMMA对复合绝缘层表面形貌、粗糙度以及器件电学性能的影响。结果表明,当PMMA厚度为40 nm时,器件的电学性能最佳。与单一的Ta2O5栅绝缘层器件相比,其场效迁移率由4.2×10-2 cm2/(V·s)提高到0.31 cm2/(V·s);栅电压增加到-20 V时,开关电流比由2.9×102增大到2.9×105。 相似文献
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Improved Performance of Organic Thin Film Transistor with an Inorganic Oxide/Polymer Double-Layer Insulator 下载免费PDF全文
We employ the Ta2Os/PVP (poly-4-vinylphenol) double-layer gate insulator to improve the performance of pentacene thin-film transistors. It is found that the double-layer insulator has low leakage current, smooth surface and considerably high capacitance. Compared to Ta205 insulator layers, the device with the Ta2Os/PVP doublelayer insulator exhibits an enhancement of the field-effect mobility from 0.21 to 0.54 cm2/Vs, and the decreasing threshold voltage from 4.38 V to -2.5 V. The results suggest that the Ta2Os/PVP double-layer insulator is a potential gate insulator for fabricating OTFTs with good electrical performance. 相似文献
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Influence of Dopant Concentration on Electroluminescent Performance of Organic White-Light-Emitting Device with Double-Emissive-Layered Structure 下载免费PDF全文
A novel phosphorescent organic white-light-emitting device (WOLED) with contiguration of ITO/NPB/CBP: TBPe:rubrene/Zn(BTZ)2:Ir(piq)2(acac)/Zn(BTZ)2/Mg:Ag is fabricated successfully, where the phosphorescent dye bis (1-(phenyl)isoquinoline) iridium (Ⅲ) acetylanetonate (Ir(piq)2 (acac)) doped into bis-(2-(2-hydroxyphenyl) benzothiazole)zinc (Zn(BTZ)2) (greenish-blue emitting material with electron transport character) as the red emitting layer, and fluorescent dye 2,5,8,11-tetra-tertbutylperylene (TBPe) and 5,6,11,12-tetraphenyl-naphthacene (rubrene) together doped into 4,4'-N,N'-dicarbazole-biphenyl (CBP) (ambipolar conductivity material) as the blue-orange emitting layer, respectively. The two emitting layers are sandwiched between the hole-transport layer N ,N'-biphenyl-N , N'-bis (1-naph thyl)-(1,1'-biphenyl)-4, 4 Cdiamine (NP B) and electron-transport layer (Zn(BTZ)2 ) The optimum device turns on at the driving voltage of 4.5 V. A maximum external quantum efficiency of 1.53%. and brightness 15000 cd/m^2 are presented. The best point of the Commission Internationale de 1'Eclairage (CIE) coordinates locates at (0.335, 0.338) at about 13 V. Moreover, we also discuss how to achieve the bright pure white light through optimizing the doping concentration of each dye from the viewpoint of energy transfer process. 相似文献
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The performance of organic light-emitting diodes (OLEDs) with thick film is optimized. The alternative vanadium oxide (V2O5) and N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB) layers are used to enhance holes in the emissive region, and 4,7-dipheny-1,10-phenanthroline (Bphen) doped 8-tris-hydroxyquinoline aluminium (Alq3) is used to enhance electrons in the emissive region, thus ITO/V2O5 (8nm)/NPB (52nm)/V2O5 (8nm)/NPB (52nm)/Alq3 (30 and 45nm)/Alq3:Bphen (30wt%, 30 and 45nm)/LiF (1nm)/Al (120nm) devices are fabricated. The thick-film devices show the turn-on voltage of about 3V and the maximal power efficiency of 4.5lm/W, which is 1.46 times higher than the conventional thin-film OLEDs. 相似文献
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A. Jasenek U. Rau T. Hahn G. Hanna M. Schmidt M. Hartmann H.W. Schock J.H. Werner B. Schattat S. Kraft K.-H. Schmid W. Bolse 《Applied Physics A: Materials Science & Processing》2000,70(6):677-680
We investigate the degradation of ZnO/CdS/ Cu(In,Ga)Se2 heterojunction solar cells for space applications and the defect generation in polycrystalline Cu(In,Ga)Se2 thin films by irradiation with 1-MeV electrons with fluences Je up to Je=5᎒18 cm-2. Notable degradation of the solar cell performance starts at fluences of Je=1017 cm-2 where the open circuit voltage decreases by about 5% while short circuit current and fill factor remain essentially unaffected. Thus, Cu(In,Ga)Se2 solar cells withstand electron fluences which are higher by one order of magnitude or more when compared to other technologies. A model describes the absolute open circuit voltage loss considering the increase of space charge recombination by electron irradiation-induced defects. Defect analysis by admittance spectroscopy shows that acceptor defects with an energy distance of approximately 300 meV from the valence band are generated at a rate %=0.017 (ǂ.01) cm-1. 相似文献
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A hypothesis is brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz (THz) band because THz wave band interspaces those two wave bands. For the purpose-of exploring a kind of low-loss material for THz waveguide, Lu2.1Bi0.9Fe5O12(LuBiIG) garnet films are prepared by liquid phase epitaxy (LPE) method on a gadolinium gallium garnet (GGG) substrate from lead-free flux because of the good properties in both optical and microwave bands. In microwave band, the ferromagnetic resonance (FMR) linewidth of the film 2△H = 2.8-5.1Oe; in optical band, the optical absorption coefficient is 600cm^-1 at visible range and about 100-170cm^-1 when the wavelength is longer than 800nm. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorbance of the film for THz wave is 0.05-0.3 cm 1 and the minimum value appears at 2.3 THz. This artificial ferromagnetic material holds a great promise for magnetic field tunable THz devices such as waveguide, modulator or switch. 相似文献