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881.
Liu XQ Lu W Shen SC Tan HH Jagadish C Zou J 《Journal of nanoscience and nanotechnology》2001,1(4):389-392
A pseudomorphic Al0.5Ga0.5As/In0.25Ga0.75As/GaAs asymmetric quantum wire (QWR) structure was grown on GaAs V-grooved substrate by low pressure metal organic vapor phase epitaxy. The formation of crescent shaped QWRs at the bottom of the V-grooves was confirmed by both transmission electron microscopy and photoluminescence (PL) spectra. The temperature dependence of PL spectra demonstrated a fast decrease of the sidewall quantum well PL intensity with increasing temperature, which originates from relaxation of carriers from well to wire region. The self-aligned dual implantation technique was successfully used to selectively disable the adjacent quantum structures. Decrease of the PL intensity of QWR at 8 K was observed after selective implantation, which resulted from a decreased number of carriers relaxed from adjacent quantum structures. 相似文献
882.
883.
Liu Zheng Jing Zhou Jie Shen Yanyuan Qi Sheng Li Shirley Shen 《Journal of Materials Science: Materials in Electronics》2018,29(20):17195-17200
PTFE-based ceramic-polymer dielectric composites have been widely researched in the communication field due to their good processing, wide range frequency and temperature stability and being able to provide tunable dielectric constant in a scale. In order to improve the compatibility between the ceramic fillers and polymer matrix without damage of dielectric properties, surface modifiers with less carbon remain are preferred. In this paper, tetraethylorthosilicate (TEOS) is employed as a surface modifier to improve the compatibility between the (Ca, Li, Sm)TiO3 (CLST) ceramic and PTFE, and the dispersion of the ceramic particles in the matrix. FTIR, XPS and TEM results indicate that TEOS is coated on the ceramic particles successfully and forms a silica coating layer. The surface modification improves the dispersion of particles in PTFE and interface contact between the ceramic fillers and PTFE matrix. These improve the thermal stability and reduce the dielectric loss of the dielectric composites. The CLST/PTFE composite modified by TEOS exhibits a dielectric constant of 6.22 with dielectric loss just 0.0012 at microwave frequencies (around 10 GHz). 相似文献
884.
Yihui Sun Xiaoqin Yan Xin Zheng Yong Li Yichong Liu Yanwei Shen Yi Ding Yue Zhang 《Nano Research》2017,10(1):77-86
The carrier screening effect occurs commonly in dielectric materials. It reduces the electric potential gradient, thus negatively affecting the functionality of resistive random access memory (RRAM) devices. An Au/ZnO film/Al-doped ZnO device fabricated in this work exhibited no resistive switching (RS), which was attributed to the carrier screening effect. Therefore, annealing was used for alleviating the screening effect, significantly enhancing the RS property. In addition, different on/off ratios were obtained for various bias values, and the screening effect was accounted for by investigating electron transport mechanisms. Furthermore, different annealing temperatures were employed to modulate the free carrier concentration in ZnO films to alleviate the screening effect. The maximal on/off ratio reached 105 at an annealing temperature of 600 °C, yielding the lowest number of free carriers and the weakest screening effect in ZnO films. This work investigates the screening effect in RS devices. The screening effect not only modulates the characteristics of memory devices but also provides insight into the mechanism of RS in these devices. 相似文献
885.
Scanning Nanowelding Lithography for Rewritable One‐Step Patterning of Sub‐50 nm High‐Aspect‐Ratio Metal Nanostructures 下载免费PDF全文
Guoqiang Liu Lina Chen Jin Liu Meng Qiu Zhuang Xie Jian Chang Yaokang Zhang Peng Li Dang Yuan Lei Zijian Zheng 《Advanced materials (Deerfield Beach, Fla.)》2018,30(35)
The development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one‐step fabrication of arbitrary high‐aspect‐ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high‐aspect‐ratio patterns, through a cold‐welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub‐50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as‐made nanostructures and rewrite them into other shapes and orientations on‐demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage–erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high‐aspect‐ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications. 相似文献
886.
Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods 下载免费PDF全文
Lei Wang Kyle Marcus Xiaojuan Huang Zhiqiang Shen Yang Yang Yingpu Bi 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(14)
An Ar atmospheric treatment is rationally used to etch and activate hematite nanoflakes (NFs) as photoanodes toward enhanced photoelectrochemical water oxidation. The formation of a highly ordered hematite nanorods (NRs) array containing a high density of oxygen vacancy is successfully prepared through in situ reduction of NFs in Ar atmosphere. Furthermore, a hematite (104) plane and an iron suboxide layer at the absorber/back‐contact interface are formed. The material defects produced by a thermal oxidation method can be critical for the morphology transformation from 2D NFs to 1D NRs. The resulting hematite NR photoanodes show high efficiency toward solar water splitting with improved light harvesting capabilities, leading to an enhanced photoresponse due to the artificially formed oxygen vacancies. 相似文献
887.
Silicon-on-Insulator (SOI) substrates incorporated with buried MoSi2 were fabricated using room temperature plasma bonding technology and smart cut technology. The molybdenum disilicide phase formation and morphology were studied by means of four-point probe measurements, X-ray diffraction analysis, atomic force microscopy and transmission electron microscopy examination. It is found that the transition of high-resistance phase Mo3Si to low-resistance phase h-MoSi2 occurs at approximately 750 °C. The t-MoSi2 phase emerges at approximately 900 °C. SOI substrate incorporated with buried silicide layer of complete t-MoSi2 phase can be achieved by 900 °C annealing for 20 min. 相似文献
888.
889.
介质薄膜的透射光谱测量及其光学参数的分析 总被引:1,自引:0,他引:1
介绍介质薄膜透射光谱的测量以及基于分析薄膜透射光谱的计算薄膜光学参数的方法。对制备在玻璃基板上的二氧化钛、二氧化硅和氧化锌薄膜进行了可见光谱区的透射比测量,并用包络线方法和最优化方法对这些透明薄膜的光学参数进行了计算和分析。着重讨论了最优化方法在分析薄膜光学参数中的应用及其误差分析。此外,还对包络线方法和最优化方法进行了比较。 相似文献
890.
Nano-multilayers represent a new class of engineering materials that are made up of alternating nanometer scale layers of two different components. In the present work a titanium (Ti) monolayer was combined with titanium diboride (TiB2) to form a Ti/TiB2 nano-multilayer. Designed experimental parameters enabled an evaluation of the effects of direct current bias voltage (Ub) and bilayer thickness (Λ) during multilayer deposition on the mechanical properties of reactively sputtered Ti/TiB2 multilayer films. Their nanostructures and mechanical properties were characterized and analyzed using X-ray photoelectron spectroscopy (XPS), low-angle and high-angle X-ray diffraction (XRD), plan-view and cross-sectional high-resolution transmission electron microscopy (HRTEM), and microindentation measurements. Under the optimal bias voltage of Ub = − 60 V, it was found that Λ (varied from 1.1 to 9.8 nm) was the most important factor which dominated the nanostructure and hardness. The hardness values obtained varied from 12 GPa for Ti and 15 GPa for TiB2 monolayers, up to 33 GPa for the hardest Ti/TiB2 multilayer at Λ = 1.9 nm. The observed hardness enhancement correlated to the layer thickness, followed a relation similar to the Hall-Petch strengthening dependence, with a generalized power of ∼ 0.6. In addition, the structural barriers between two materials (hcp Ti/amorphous TiB2) and stress relaxation at interfaces within multilayer films resulted in a reduction of crack propagation and high-hardness. 相似文献