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Thin films of Zinc Oxide were deposited by the sol-gel technique on glass substrates. The films were doped with Al, Mg or co-doped with both by introduction of appropriate compounds in the solution before dip-coating and annealing in air at 500 °C. Energy Dispersive X-Ray Spectroscopy was employed to measure the dopant incorporation. X-ray diffraction studies indicate that Mg doping increases grain size, while Al doping reduces it. Photoluminescence (PL) measurements indicate that undoped and Al-doped films show, along with a broad near band-edge (NBE) peak, additional peaks at longer wavelengths related to various defect states. However Mg doped films show only a sharp NBE peak, which is blue shifted compared to undoped ZnO, and there are no prominent sub band gap luminescence peaks. This is also the case for Mg and Al co-doped ZnO samples, provided the Mg content is low. Photocurrent measurements were carried out using silver contacts using a De source under atmospheric conditions. Undoped and Mg doped ZnO films showed high resistances and low photocurrent levels. With low Al doping, both the dark current and the photocurrent increase significantly, but the films show very long photocurrent transients. With optimized concentration of Mg/Al co-doping in ZnO, the photocurrent increased by ~98 times compared to ZnO films doped only with Mg. Simultaneously, the photocurrent transients became ~44 times faster than ZnO films doped only with Al. 相似文献
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《Advanced Electronic Materials》2017,3(8)
Ultraviolet (UV) monitoring has wide applications in diverse fields, where sensitive photodetection and recording of UV exposure history are often simultaneously required. A new strategy is herein developed to achieve solar‐blind UV monitoring. Based on organic field‐effect transistors (OFETs), nonvolatile memories with both p‐type or n‐type organic active layers demonstrate selective and storable UV response. These OFET memories are sensitive only to solar‐blind UV light of 254 nm, and have no response to UV light of 365 nm or visible light. The photoresponsive signal can be recorded in a nonvolatile manner with excellent retention and rewritable capability, which integrates solar‐blind UV detection and memory into a single device. These OFET memories are well compatible with flexible substrates, and thus could be very useful for portable and/or wearable UV dosimetry. The conventional bandgap photoexcitation mechanism is not applicable to the this case, and a UV‐induced interfacial excitation mechanism is proposed to interpret the device features. 相似文献
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Yusi Yang Shun‐Chang Liu Xia Wang Zongbao Li Yun Zhang Gengmin Zhang Ding‐Jiang Xue Jin‐Song Hu 《Advanced functional materials》2019,29(16)
Polarization‐sensitive photodetection in the UV region is highly indispensable in many military and civilian applications. UV‐polarized photodetection usually relies on the use of wide bandgap semiconductors with 1D nanostructures requiring complicated nanofabrication processes. Although the emerging anisotropic 2D semiconductors shed light on the detection of polarization with a simple device architecture, bandgaps of such reported 2D semiconductors are too small to be applied for visible–blind UV‐polarized photodetection. Here, germanium disulfide (GeS2), the widest bandgap (>3 eV) in the family of in‐plane anisotropic 2D semiconductors explored to date, is introduced as an ideal candidate for UV‐polarized photodetection. The structural, vibrational, and optical anisotropies of GeS2 are systematically investigated from theory to experiment. GeS2‐based photodetectors show a strong polarization‐dependent photoresponse in the UV region. GeS2 with a wide bandgap and high in‐plane anisotropy not only enriches the family of anisotropic 2D semiconductors but also expands the polarized photodetection from the current visible and near‐infrared to the brand‐new UV region. 相似文献
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Suo Bai Weiwei Wu Yong Qin Nuanyang Cui Dylan J. Bayerl Xudong Wang 《Advanced functional materials》2011,21(23):4464-4469
Due to the large surface area‐to‐volume ratio and high quality crystal structure, single nanowire (NW)‐based UV sensors exhibit very high on/off ratios between photoresponse current and dark current. Practical applications require a large‐scale and low‐cost integration, compatibility to flexible electronics, as well as reasonably high photoresponse current that can be detected without high‐precision measurement systems. In this paper, NW‐based UV sensors were fabricated in large‐scale by integrating multiple NWs connected in parallel via the contact printing method. Linear scaling of the photoresponse current with the number of NWs is demonstrated. Integrated ZnO NW UV sensors were fabricated on rigid glass and flexible polyester (PET) substrates at the macroscopic scale. The flexible and rigid sensors performed comparably, exhibiting on/off current ratios approximately three orders of magnitude higher than sensors made from polycrystalline ZnO thin films. Under UV irradiance of 4.5 mW cm?2 and 3 V bias, photoresponse currents and on/off current ratios for the rigid and flexible UV sensors reached 12.22 mA and 82 000, and 14.1 mA and 120 000, respectively. This result suggests that lateral integration of semiconductor NWs is an effective approach to large‐scale fabrication of flexible NW sensors that inherit the merits of single‐NW‐based systems with unaffected performance compared to using rigid substrate. 相似文献
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自组装技术起源于生物化学领域。20世纪90年代以来,这种新型的装配技术得到了关注并且经历了较快的发展,同时在微机电系统(MEMS)等研究领域显示了潜在的应用前景。本文阐述了自组装技术的发展,介绍了多种自组装方法,包括利用毛细力、重力以及亲水(疏水)力作为驱动的多种自组装过程,着重总结了自组装技术在MEMS领域的应用。 相似文献
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以Al2O3、Y2O3(质量比为2:3)为烧结助剂,在氮气氛或氩气氛中、1900～1970℃、30 MPa下热压制备SiC陶瓷.根据Archimedes原理测量烧结体的体积密度和显气孔率;采用XRD、SEM(EDS)及瞬态热导率测试仪分别对材料的物相、显微结构和热导率进行表征.研究了烧结温度、烧结气氛和烧结助剂含量对材料烧结性能和热导率的影响.结果表明,当烧结助剂质量分数为10%,获得SiC致密体(气孔率＜0.30%),热导率高达182.50 W/(m·K);随着烧结助剂的质量分数降至6%,材料的致密度和热导率皆明显下降;在氩气氛中SiC与Al2O3、Y2O3具有更好的润湿性. 相似文献
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J. W. Dong A. Osinsky B. Hertog A. M. Dabiran P. P. Chow Y. W. Heo D. P. Norton S. J. Pearton 《Journal of Electronic Materials》2005,34(4):416-423
We report on the fabrication and characterization of an ultraviolet (UV) light-emitting diode (LED) based on a p-n junction
MgZnO/ZnO/AlGaN/GaN semiconductor triple-heterostructure (THS). Radio-frequency (RF) plasma-assisted molecular-beam epitaxy
(MBE) has been employed to grow individual epitaxial layers of ZnO, MgxZn1−xO, and the complete heterostructure on c-plane GaN/sapphire templates. Various growth strategies have been used to optimize
the quality of the ZnO layers as well as to precisely control the composition of the MgxZn1−xO compound. Cross-sectional transmission electron microscopy (TEM) study shows the excellent crystalline quality of the pseudomorphically
grown ZnO active region of the device. A strong electroluminescence (EL) emission associated with ZnO excitonic transition
was observed up to 650 K. The results shown in this paper strongly suggest the viability of RF plasma-assisted MBE in the
development of next-generation UV emitters using ZnO-based materials. 相似文献
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研究和制作了一种新型Au/n-ZnO/p-Si结构的肖特基发射极、异质结集电极紫外增强双极型光电三极管.分析了器件原理,测试了I-V特性、C-V特性以及器件的光谱响应,从200到400nm的紫外光响应灵敏度得到明显增强而对大于400nm的可见光的响应特性得到保留.实验显示Au/n-ZnO/p-Si结构的紫外增强型的光电三极管对紫外光的响应明显增强,对371nm波长的紫外光的灵敏度是普通n-ZnO/p-Si异质结紫外光电二极管道的5～10倍. 相似文献
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俞铄城 《固体电子学研究与进展》2024,44(1):84-91
针对当前高温功率芯片耐高温封装连接问题,评述了国内外新型无铅高温焊料、纳米颗粒烧结技术、瞬时液相连接和瞬时液相烧结（Transient liquid phase sintering, TLPS）技术的研究现状和动态,分析了各种技术的优缺点。分析发现纳米颗粒材料和TLPS 连接技术应用于高温器件封装时具有低温连接、高温服役的显著优势。但纳米颗粒材料烧结过程中存在有机物难以挥发、Cu纳米颗粒易被氧化、Ag纳米颗粒接头中的电迁移等问题;TLPS烧结过程中由于有机粘结剂的挥发以及颗粒物体积收缩,致使接头产生孔洞,导致接头的电导率和热导率降低。这些问题可以通过合金元素的添加、工艺的改进,以及焊料的复合化加以解决,这将推动高温电子封装行业的发展。 相似文献
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Directional liquid-transport surfaces have various applications, such as, open microfluidic devices, fog collection, oil–water separation, and surface lubrication. However, current liquid-transport surfaces are expensive, complicated to manufacture, and lack scalability. Moreover, they exhibit low transport speeds and distances. In this study, a laser cutter is used to fabricate scalable, low-cost unidirectional liquid-transporting surfaces with enhanced transport speed and distance using polymeric materials. Cutting and engraving methods are used to create a liquid capillary diode comprising 3D wedge shapes, thereby obtaining an appropriate pressure gradient and liquid pinning. The developed liquid capillary diode exhibits the fastest transport speed (3–17.7 mm s−1) reported so far, and a large normalized distance (L/R: transport distance/radius of dispensed droplet). The transport distance increases with the square root of time under various contact angles and liquid viscosities, which agree well with the theoretical scaling results obtained using the modified Washburn model. Additionally, the flexible liquid capillary diode operates adequately even when bent with the maximum curvature of 0.1 mm−1. The results provide better design guidelines for 3D topological liquid-transport surfaces for various applications. 相似文献
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研究和制作了一种新型Au/n-ZnO/p-Si结构的肖特基发射极、异质结集电极紫外增强双极型光电三极管.分析了器件原理,测试了I-V特性、C-V特性以及器件的光谱响应,从200到400nm的紫外光响应灵敏度得到明显增强而对大于400nm的可见光的响应特性得到保留.实验显示Au/n-ZnO/p-Si结构的紫外增强型的光电三极管对紫外光的响应明显增强,对371nm波长的紫外光的灵敏度是普通n-ZnO/p-Si异质结紫外光电二极管道的5～10倍. 相似文献
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Hua-Lu Zhuang Jun Pei Bowen Cai Jinfeng Dong Haihua Hu Fu-Hua Sun Yu Pan Gerald Jeffrey Snyder Jing-Feng Li 《Advanced functional materials》2021,31(15):2009681
The widespread application of thermoelectric (TE) technology demands high-performance materials, which has stimulated unceasing efforts devoted to the performance enhancement of Bi2Te3-based commercialized thermoelectric materials. This study highlights the importance of the synthesis process for high-performance achievement and demonstrates that the enhancement of the thermoelectric performance of (Bi,Sb)2Te3 can be achieved by applying cyclic spark plasma sintering to BixSb2–xTe3-Te above its eutectic temperature. This facile process results in a unique microstructure characterized by the growth of grains and plentiful nanostructures. The enlarged grains lead to high charge carrier mobility that boosts the power factor. The abundant dislocations originating from the plastic deformation during cyclic liquid phase sintering and the pinning effect by the Sb-rich nano-precipitates result in low lattice thermal conductivity. Therefore, a high ZT value of over 1.46 is achieved, which is 50% higher than conventionally spark-plasma-sintered (Bi,Sb)2Te3. The proposed cyclic spark plasma liquid phase sintering process for TE performance enhancement is validated by the representative (Bi,Sb)2Te3 thermoelectric alloy and is applicable for other telluride-based materials. 相似文献
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Yuchen Hou Congcong Wu Xu Huang Dong Yang Tao Ye Jungjin Yoon Rammohan Sriramdas Kai Wang Shashank Priya 《Advanced functional materials》2021,31(7):2007016
Narrowband photodetector (NB-PD) with selective light detection is critical for artificial vision and imaging. Intrinsic (optical-filter-free) NB-PDs using conjugated organics or halide perovskite materials have been developed for eliminating the current complex filtering systems in NB-PDs. However, the poor performance and external driving circuit of organic NB-PDs as well as complex doping and uncontrollable recombination reactions in typical perovskite NB-PDs have limited their applicational diversification. A p-type self-doped perovskite for intrinsic NB detection is reported which exhibits unique unbalanced electron–hole transfer kinetics. In conjunction with the optical field distribution, an unbalanced charge transport within the self-doped perovskite triggers a wavelength-dependent photo-carrier collection, resulting in a novel spontaneous internal quantum efficiency narrowing mechanism. As a result, by reverting the device architectural polarity, an NB detection at a monochromic light of either red or UV is observed. Using such a revertible asymmetric device design, self-powered NB-PDs are successfully achieved. Briefly, the corresponding NB-PDs exhibit excellent narrow response with a response window of ≈100 nm, high detectivity ≈1011 Jones, and fast response speed (f−3dB ≈ 60 kHz) at zero bias. These results demonstrate a new strategy of manipulating internal charge transport to realize power-free and filter-free intrinsic NB-PDs. 相似文献