国内精品久久毛片一区二区,久久人人97超碰a片精品,破了亲妺妺的处免费视频国产 ,性做久久久久久

技術(shù)文章

Technical articles

當(dāng)前位置:首頁技術(shù)文章In Situ Assembly of Ordered Hierarchical CuO Microhemisphere Nanowire Arrays for High-Performance

In Situ Assembly of Ordered Hierarchical CuO Microhemisphere Nanowire Arrays for High-Performance

更新時間:2021-06-01點擊次數(shù):2268

In Situ Assembly of Ordered Hierarchical CuO Microhemisphere Nanowire Arrays for High-

        Performance Bifunctional Sensing Applications Tiantian Dai, Zanhong Deng, Xiaodong Fang,* Huadong Lu, Yong He, Junqing Chang, Shimao Wang, Nengwei Zhu, Liang Li,* and Gang Meng*

1. Introduction

       Device fabrication/integration is a longstanding challenge issue for the practical application of metal oxide nanowires with distinctive physiochemical and unique quasi-1D geometric properties.[1–3] In comparison with conventional planar nanowire devices, in which postsynthesis alignment (Langmuir–Blodgett technique,[4] contact printing,[5] and blow bubble,[6] etc.) is first employed and then electrodes are deposited, by directly growing nanowires on the selected area of solid substrates with bottom electrodes, when the tips of nanowires growing on the counter electrodes encompass each other and form stable junctions, a “bridged” nanowire device could be formed (at a large scale) in an in situ manner.[7–10] Apart from the superior benefits of facile integration of nanowire devices, bridged nanowire devices outperform conventional planar nanowire devices in several aspects. First, in situ growth ensures good electrical contact between the nanowires and the underlying electrode,[11] which plays an essential role in the performance of diverse microelectronic devices, including sensors,[12] photodetectors,[13] field emitters,[14] and energy storage devices.[15] Second, a nonplanar (or suspended) configuration not only avoids carrier scattering at the nanowire/substrate interface (leading to increased mobility)[16] but also offers a maximal exposure surface for analyte molecule adsorption (acting as a gate-all-around effect) and thus offers an additional avenue for designing highly sensitive sensors with ultralow power consumption.[7,11,17,18] As an important p-type oxide with versatile properties, CuO nanowires have promising applications in molecular sensors for harmful vapor monitoring,[19–23] photodetectors,[24] field emitting devices,[25] energy storage devices,[26] etc. Previous studies indicate that the number and density of bridged nanowires play an important role in the device performance (i.e., response and power consumption of gas sensors),[7,27] therefore, a rational synthesis methodology is essential for constructing high-performance devices. Though thermal oxidation of Cu (powder, foil, wire, film, etc.) offers a simple and catalyst-free method[28,29] for anisotropic growth of CuO nanowires, driven by oxidation induced strain between the CuO/Cu2O interfaces, as well as the fast outer diffusivity of Cu ions across the CuO/ Cu2O/Cu interfaces[29,30] and thermal oxidation of Cu powder or sputtered (patterned) Cu film dispersed/deposited onto the electrode substrate enabling the formation of bridged nanowires,[8,19] weak adhesion (due to thermal oxidation induced strain),[31] poor uniformity and uncontrolled electrical pathways hinder their promising applications. In this work, a novel methodology based on dewetting of patterned Cu films to create ordered Cu microhemisphere arrays was reported. Ag layer was proposed as a sacrificial layer to assist the dewetting of Ag/Cu/Ag films into microhemispheres at a relatively low temperature of 850 °C. Sacrificial Ag could be readily removed by vacuum evaporation due to the higher vapor pressure of Ag than Cu. In comparison with previously reported Cu powder or Cu film devices, Ag-assisted dewetting significantly shrinks the contact area of Cu/substrate to ≈1–500 µm2 (depending on size), which allows effective release of the interfacial stress during thermal oxidation of Cu[31] and contributes to firm adhesion with the underlying substrate. In addition, the position and size of hemisphere Cu arrays could be readily controlled, which plays a vital role in manipulating the structural properties (diameter, length and bridging density of nanowires) of CuO nanowires grown by thermal oxidation on diverse insulator substrates with indium tin oxide (ITO) electrodes. The in situ formed regularly bridged CuO microhemisphere nanowire arrays (RB-MNAs) devices exhibit much higher gas molecule and light responses than irregularly bridged microsphere nanowires (IB-MNs) devices, fabricated by thermal oxidation of Cu powder dispersed on ITO electrode substrates. For example, the electrical response (toward 100 ppm trimethylamine, TMA) of the RB-MNAs device is 2.8 times as high as that of the IB-MNs device at an operation temperature of 310  °C. The on/off current ratio toward (15.6  mW cm−2 ) 810  nm of the RB-MNAs device is 1.5 times as high as that of the IB-MNs device. Finally, 4 × 4 RB-MNAs devices were integrated onto a transparent ITO/quartz wafer, demonstrating the potential of the present methodology for the mass production of bridged CuO nanowire devices for future applications.

 2. Results and Discussion

        Although dewetting of uniform patterned metal films offers an approach to obtain homogeneous metal micro/nanoparticle arrays,[32,33] dewetting of patterned Cu films (prepared by using Ni shadow masks, the geometric parameters are listed in Table S1, Supporting Information) fails even at a high temperature of 850  °C. The high melting point of Cu (1085  °C) probably hinders the shrinking of the patterned Cu film at 850  °C (Figure S1, Supporting Information). Binary Cu-metal phase diagrams indicate that CuAg alloy (with 71.9 wt% Ag) possesses a low melting temperature of 779 °C,[34] which suggests that alloying with Ag may facilitate the dewetting of Cu film. Moreover, as the vapor pressure of Ag is much higher than that of Cu, Ag may be removed by appropriate thermal evaporation. Inspired by the abovementioned analysis, the patterned Cu film was sandwiched between the top and bottom Ag sacrificial layers (Ag/Cu/Ag) on a SiO2/Si or quartz substrate coated by ITO interdigital electrode (Figure 1a,e). As expected, the Ag/Cu/Ag film (size of 10.5  µm, thickness of 1.2/1.2/1.2  µm, with a Ag weight ratio of ≈70%) could be dewetted into a hemisphere shape (inset of Figure 1f) via vacuum or inert gas atmosphere annealing in a tube furnace (to prevent oxidation of metals) at 850 °C (Figure 1b,f). A noticeable decrease in the diameter of hemispheres from 8.0 ± 0.3 µm (Figure S2a, Supporting Information) to 7.0  ± 0.3 µm (Figure S2b, Supporting Information) was observed after performing vacuum evaporation (850 °C, 0.1 Pa, 1 h) (Figure 1c,g and Figure S2, Supporting Information). Moreover, the appearance of a dark condensed metal film in the low-temperature zone of the quartz tube furnace infers the evaporation of Ag, because the vapor pressure of Ag (≈2.8 × 10−1  Pa) is much higher than that of Cu (≈2.3 × 10−3  Pa) at 850  °C.[35] Thermal oxidation of ordered Cu microhemispheres at 400–450  °C allows the formation of ordered hierarchical CuO microhemisphere nanowires (Figure  1d,h). Specifically, when the nanowires grown from adjacent Cu spheres contact each other, a bridged nanowire device could be formed in an “in situ” manner. To monitor the variation of sacrificial Ag, energy dispersive spectrometry (EDS) analysis was performed (Figure 1i–l). Pristine Ag/Cu/Ag shows a higher Ag ratio (78.5  wt%) than the nominal ratio (70.3 wt%), as EDS is a surface analysis method that can only collect the generated X-ray signal in a region of ≈2 µm in depth depending on the atomic number,[36] which is less than the thickness of the Ag/ Cu/Ag film (≈3.6  µm) in Figure  1e. The substantial decrease in the Ag component in the CuAg alloy from 62.7  wt% (Figure  1j) to a negligible 0.2 wt% (Figure  1k) via vacuum evaporation suggests that most of the sacrificial Ag was evaporated. Appearance of O signal in the dewetted CuAg and Cu hemispheres (Figure  1j,k) may arise from trace oxidization by remaining oxygen in the vacuum (≈0.1 Pa) tube furnace during dewetting and evaporation process. Moreover, the tiny variation in Cu volume from the initial Cu film (Figure 1e) to the hemisphere (Figure  1g) infers that Cu was maintained during the dewetting and evaporation process. The use of a Ag sacrificiallayer allows the fabrication of ordered Cu microhemisphere arrays (Figure  1c,g) on a solid substrate and further obtains ordered hierarchical CuO microhemisphere nanowire arrays (Figure 1d,h).

 

 

 

 

 

 

 

 

以上論文信息不完整    感謝中科大的孟老師對微型探針臺的反饋!需要詳細的文獻,請到中科院一區(qū)  影響因子12    感謝所有的科研奉獻者辛勞的付出。

无码国产激情在线观看| 老师黑色双开真丝旗袍| 15女上课自慰被男同桌看到了| 纯肉大根巨无霸纯黑胡椒火腿肠 | 动漫AV纯肉无码AV在线播放 | 亚洲gv钙片在线观看网站| 日产国产亚洲精品系列p| 久久久精品一区aaa片| 天天做天天爱夜夜爽毛片毛片| 奇米777狠狠888俺也去| 意大利电影奸情| 少妇多水xxxx色情免费| 国产另类ts人妖一区二区| 圣女当众被迫高潮h高| japanese成熟丰满熟妇| 成人乱码一区二区三区av| 亚洲最大AV资源站无码AV网址| 偿还HD韩国中文版| 放荡少妇交换超级乱| 51国偷自产一区二区三区| 第一次进入女朋友的身体注意事项| 浪荡货老子大吗爽死你h漫画男男| 亚洲av片在线观看| 免费看男男gay啪啪网站| 亚洲av无码专区国产精品麻豆| 3男s调教玩弄一女m文 | 人世间电视剧免费观看全集完整版| 国产97在线 | 免费| 欧美在线香蕉在线视频| 国产美女精品一区二区三区| 亲嘴扒胸摸屁股激烈网站| CHINESE老熟妇老女人HD| 教官脱了男生衣服摸j的故事| 小莹与翁回乡下欢爱姿势| 女子初尝黑人巨嗷嗷叫| 新婚之夜玩弄人妻系列| 亚洲444KKKK在线观看无码 | 精品人妻人人爽久久爽av蜜桃| 叶辰萧初然最新更新章节免费阅读| 一本大道无码人妻精品专区| 国产一二三精品无码不卡日本|