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Simulation and structure optimization of triboelectric nanogenerators considering the effects of parasitic capacitance

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nano Research 2017年第1期10卷 157-171页

作者： Keren Dai Xiaofeng Wang Simiao Niu Fang Yi Yajiang Yin Long Chen Yue Zhang Zheng You Collaborative Innovation Center for Micro/Nano Fabrication Device and System State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instrument Tsinghua University Beijing 100084 China School of Materials Science and Engineering Georgia Institute of Technology Atlanta GA30332-0245 USA State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering Bei)ing Municipal Key Laboratory of New Energy Materials and Technologies University of Science and Technology Beijing Beijing 100083 China Broadcom Ltd. 2901 Via Fortuna #400 Austin TX 78746 USA

Parasitic capacitance is an unavoidable and usually unwanted capacitance that exists in electric circuits, and it is the most important second-order non-ideal effect that must be considered while designing a triboelectric nanogenerator （TENG） because its magnitude is comparable to the magnitude of the TENG capacitance. This paper investigates the structure and performance optimization of TENGs through modeling and simulation, taking the parasitic capacitance into account. Parasitic capacitance is generally found to cause severe performance degradation in TENGs, and its effects on the optimum matching resistance, maximum output power, and structural figures-of-merit （FOMs） of TENGs are thoroughly investigated and discussed. Optimum values of important structural parameters such as the gap and electrode length are determined for the different working modes of TENGs, systematically demonstrating how these optimum structural parameters change as functions of the parasitic capacitance. Additionally, it is demonstrated that the parasitic capacitance can improve the height tolerance of the metal freestanding-mode TENGs. This work provides a theoretical foundation for the structure and performance optimization of TENGs for practical applications and promotes the development of mechanical energy-harvesting techniques.

关键词： triboelectric nanogenerator parasitic capacitance figure of merit structure optimization performance optimization

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Thick SU8 microstructures prepared by broadband UV lithography and the applications in MEMS devices

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Optoelectronics Letters 2016年第3期12卷 182-187页

作者：李东玲温志渝尚正国佘引 National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China Micro System Reaserch CenterChongqing University

Thick SU8 microstructures with high aspect ratio and good side wall quality were fabricated by ultraviolet （UV） lithography, and the processing parameters were comprehensively studied. It proves that the adhesion of SU8 on silicon （Si） substrates is influenced by Si-OH on the surface, and can be improved by the HF treatment. Cracks and de- lamination are caused by large internal stress during fabrication process, and are significantly influenced by soft bake and post-exposure bake processes. The internal stress is reduced by a low post-exposure bake exposure tem- perature of 85 ℃ for 40 rain. A three-step soft bake enhances the reflowing ofSU8 photoresist, and results in uni- form surface and less air bubbles. The vertical side wall is obtained with the optimized exposure dose of 800 mJ/cm2 for the thickness of 160 μm. Using the optimized fabrication process combined with a proper structure design, dense SU8 micro pillars are achieved with the aspect ratio of 10 and the taper angle of 89.86°. Finally, some possible ap- plications of SU8 in micro-electromechanical system （MEMS） device are developed and demonstrated.

关键词： MEMS器件紫外光刻微结构应用微机电系统烘烤过程编写宽带

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Valley filtering effect of phonons in graphene with a grain boundary

arXiv

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arXiv 2019年

作者： Chen, Xiaobin Xu, Yong Wang, Jian Guo, Hong State Key Laboratory on Tunable laser Technology Ministry of Industry Information Technology Key Lab of Micro-Nano Optoelectronic Information System School of Science Harbin Institute of Technology Shenzhen518055 China Department of Physics Center of Theoretical and Computational Physics University of Hong Kong Hong Kong Hong Kong Collaborative Innovation Center of Quantum Matter State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China University of Hong Kong Shenzhen Institute of Research and Innovation Shenzhen518053 China College of Physics and Energy Shenzhen University Shenzhen518060 China Department of Physics 3600 University McGill University MontrealQCH3A 2T8 Canada

Due to their possibility to encode information and realize low-energy-consumption quantum devices, control and manipulation of the valley degree of freedom have been widely studied in electronic systems. In contrast, the phononic counterpart–valley phononics–has been largely unexplored, despite the importance in both fundamental science and practical applications. In this work, we demonstrate that the control of "valleys" is also applicable for phonons in graphene by using a grain boundary. In particular, perfect valley filtering effect is observed at certain energy windows for flexural modes and found to be closely related to the anisotropy of phonon valley pockets. Moreover, valley filtering may be further improved using Fano-like resonance. Our findings reveal the possibility of valley phononics, paving the road towards purposeful phonon engineering and future valley phononics. Copyright © 2019, The Authors. All rights reserved.

关键词： Landforms

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Design and fabrication of an surface acoustic wave resonator based on AlN/4H-SiC material for harsh environments

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2017年第1期18卷 67-74页

作者： Wei-zhong WANG Ji LIANG Yong RUAN Wei PANG Zheng YOU Collaborative Innovation Center for Micro/Nano Fabrication Device and System State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instrument Tsinghua University Beijing 100084 China State Key Laboratory of Precision Measurement Technology and lnstruments Tianjin University Tianjin 300072 China

Surface acoustic wave （SAW） sensors and micro-electromechanical system （MEMS） technology provide a promising solution for measurement in harsh environments such as gas turbines. In this paper, a SAW resonator （size： 1107μm× 721 μm） based on the AlN/4H-SiC multilayer structure is designed and simulated. A MEMS-compatible fabrication process is employed to fabricate the resonator. The results show that highly c-axis-oriented AlN thin films deposited on the 4H-SiC substrate are obtained, with that the diffraction peak of AlN is 36.10° and the lowest full width at half maximum （FWHM） value is only 1.19°. The test results of the network analyzer are consistent with the simulation curve, which is very encouraging and indicates that our work is a significant attempt to solve the measurement problems mainly including high temperature stability of sensitive structures and the heat transmission of leads in harsh environments. It is essential to get the best performance of SAW resonator, optimize and characterize the behaviors in high temperatures in future research.

关键词： Surface acoustic wave （SAW） resonator AlN/4H-SiC Harsh environment micro-electromechanical system（MEMS） technology Gas turbine

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Phase-encoded RF signal generation based on an integrated 49GHz micro-comb optical source

arXiv

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arXiv 2019年

作者： Xu, Xingyuan Tan, Mengxi Wu, Jiayang Boes, Andreas Corcoran, Bill Nguyen, Thach G. Chu, Sai T. Little, Brent E. Morandotti, Roberto Mitchell, Arnan Moss, David J. Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia School of Engineering RMIT University MelbourneVIC3001 Australia Department of Electrical and Computer System Engineering Monash University ClaytonVIC3168 Australia Department of Physics City University of Hong Kong Tat Chee Avenue Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'An China INSR-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

We demonstrate photonic RF phase encoding based on an integrated micro-comb source. By assembling single-cycle Gaussian pulse replicas using a transversal filtering structure, phase encoded waveforms can be generated by programming the weights of the wavelength channels. This approach eliminates the need for RF signal generators for RF carrier generation or arbitrary waveform generators for phase encoded signal generation. A large number of wavelengths—up to 60—were provided by the microcomb source, yielding a high pulse compression ratio of 30. Reconfigurable phase encoding rates ranging from 2 to 6 Gb/s were achieved by adjusting the length of each phase code. This work demonstrates the significant potentials of this microcomb-based approach to achieve high-speed RF photonic phase encoding with low cost and footprint. Copyright © 2019, The Authors. All rights reserved.

关键词： Signal encoding

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Photonic based phase-encoded RF signal generation for advanced radar systems with a 49GHz soliton crystal micro-comb optical source

TechRxiv

引用

TechRxiv 2019年

作者： Xu, Xingyuan Tan, Mengxi Wu, Jiayang Boes, Andreas Corcoran, Bill Nguyen, Thach G. Chu, Sai T. Little, Brent E. Morandotti, Roberto Mitchell, Arnan Moss, David J. The Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia The School of Engineering RMIT University MelbourneVIC3001 Australia The Department of Electrical and Computer System Engineering Monash University ClaytonVIC3168 Australia The Department of Physics City University of Hong Kong Tat Chee Avenue Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'An China INSR-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada The Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

关键词： Signal encoding

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Flexible and transparent triboelectric nanogenerator based on high performance well-ordered porous PDMS dielectric film

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nano Research 2016年第12期9卷 3714-3724页

作者： Xianming He Xiaojing Mu Quan Wen Zhiyu Wen Jun Yang Chenguo Hu Haofei Shi Department of Applied Physics Chongqing University Chongqing 400044 China Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology Chongqing University Chongqing 400044 China Microsystem Research Center Chongqing University Chongqing 400044 China Key Laboratory of Multi-Scale Manufacturing Technology Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing 400714 China

A flexible and transparent triboelectric nanogenerator （FT-TENG） has great potential for application in self-powered biosensor systems, electronic skin and wearable electronic devices. However, improving the output performance with little damage to its optical properties is challenging. Herein, we have developed an FT-TENG that has a well-ordered nest-like porous polydimethylsiloxane （NP-PDMS） film and graphene transparent electrodes. The NP-PDMS film with ordered pores is fabricated by hydrochloric acid etching of 500 nm sized ZnO spheres made of aggregated nanoparticles, having a light transmittance of 81.8% and a water contact angle of 118.62°. The FT-TENG based on the NP-PDMS film with a porosity of 12%, gives a maximum output of 271 V and 7.8 μA, which are respectively, 3.7 and 2.1-fold of those of a TENG with a flat PDMS film. The peak output power reaches 0.39 mW with a load resistance of 9.01 MΩ. The dielectric constant and effective thickness of the NP-PDMS film and the capacitance and charge transfer of the FT-TENG are systematically investigated. This work provides a novel and effective method to enhance the performance of FT-TENGs with little damage to their optical properties.

关键词： porouspolydimethylsiloxane（PDMS） surface charge density nanogenerator flexibility transparent electrode

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Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

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Optoelectronics Letters 2016年第4期12卷 285-289页

作者：李东玲冯小飞温志渝尚正国佘引 National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology Chongqing University Chongqing 400030 China Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China Chongqing University Chongqing 400030 China No.24 Reaearch Institute of China Electronics Technology Group Corporation Chongqing 400060 China

Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/LF) mode. By optimizing process parameters, stress free(-0.27 MPa) Si Nx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited Si Nx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit(IC), micro-electro-mechanical systems(MEMS) and bio-MEMS.

关键词： Deposition Deposition rates Integrated circuits MEMS Nitrides Optical properties Plasma CVD Refractive index Silicon nitride Stresses Vapor deposition

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High-Performance Photo-Modulated Thin-Film Transistor Based on Quantum dots/Reduced Graphene Oxide Fragment-Decorated ZnO nanowires

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nano-micro Letters 2016年第3期8卷 247-253页

作者： Zhi Tao Yi-an Huang Xiang Liu Jing Chen Wei Lei Xiaofeng Wang Lingfeng Pan Jiangyong Pan Qianqian Huang Zichen Zhang School of Electronic Science and Engineering Southeast University State Key Laboratory of Precision Measurement Technology and Instruments Collaborative Innovation Center for Micro/Nano Fabrication Device and System Department of Precision Instrument Tsinghua University School of Information and Communication Engineering Beijing University of Posts and Telecommunications Institute of Semiconductors Chinese Academy of Science

In this paper, a photo-modulated transistor based on the thin-film transistor structure was fabricated on the flexible substrate by spin-coating and magnetron sputtering. A novel hybrid material that composed of Cd Se quantum dots and reduced graphene oxide(RGO) fragment-decorated ZnO nanowires was synthesized to overcome the narrow optical sensitive waveband and enhance the photo-responsivity. Due to the enrichment of the interface and heterostructure by RGO fragments being utilized, the photo-responsivity of the transistor was improved to 2000 AW^(-1) and the photo-sensitive wavelength was extended from ultraviolet to visible. In addition, a positive back-gate voltage was employed to reduce the Schottky barrier width of RGO fragments and ZnO nanowires. As a result, the amount of carriers was increased by 10 folds via the modulation of back-gate voltage. With these inherent properties, such as integrated circuit capability and wide optical sensitive waveband, the transistor will manifest great potential in the future applications in photodetectors.

关键词： Thin-film transistor Quantum dots Reduced graphene oxide ZnO nanowires

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Solar Driven Spintronics: Sunlight Control of Interfacial Magnetism for Solar Driven Spintronic Applications (Adv. Sci. 24/2019)

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Advanced science 2019年第24期6卷 1970147-1970147页

作者： Yifan Zhao Shishun Zhao Lei Wang Ziyao Zhou Junxue Liu Tai Min Bin Peng Zhongqiang Hu Shengye Jin Ming Liu Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education and International Center for Dielectric Research School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China International Joint Laboratory for Micro/Nano Manufacture and Measurement Technology Xi'an Jiaotong University Xi'an 710049 China Center for Spintronics and Quantum System State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China State Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM) Dalian Institute of Chemical Physics Chinese Academy of Sciences 457 Zhongshan Rd. Dalian 116023 China

In article number https://***/10.1002/advs.201901994 , Ziyao Zhou, Ming Liu, and co‐workers propose a prototype photovoltaic spintronic device with an optical‐magneto‐electric tri‐coupled photovoltaic/magnetic thin film heterojunction, where magnetism can be manipulated directly by sunlight. Both in situ experiments and the first principle calculation results reveal that the photogenerated electrons doping in the cobalt film alter the band filling of this ferromagnetic film and manipulate the magnetization and magnetic anisotropy effectively.

关键词： ferromagnetic resonance low power magnetoelectric coupling organics solar cells

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