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Your search keyword '"Qin, Shi-Qiao"' showing total 31 results
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31 results on '"Qin, Shi-Qiao"'

6. Tunable terahertz and optical metamaterials

Author

张检发 Zhang Jianfa, 秦石乔 Qin Shi-qiao, and 袁晓东 Yuan Xiaodong

Subjects
Materials science, business.industry, Terahertz radiation, General Engineering, Optoelectronics, business, Photonic metamaterial
Published
2014

7. Ultrathin Al Oxide Seed Layer for Atomic Layer Deposition of High-κ Al2O3 Dielectrics on Graphene.

Author

Yang, Hang, Chen, Wei, Li, Ming-Yang, Xiong, Feng, Wang, Guang, Zhang, Sen, Deng, Chu-Yun, Peng, Gang, and Qin, Shi-Qiao

Subjects
ATOMIC layer deposition, FIELD-effect transistors, GRAPHENE, DIELECTRICS, PERMITTIVITY, INDIUM gallium zinc oxide
Abstract

Due to the lack of surface dangling bonds in graphene, the direct growth of high-κ films via atomic layer deposition (ALD) technique often produces the dielectrics with a poor quality, which hinders its integration in modern semiconductor industry. Previous pretreatment approaches, such as chemical functionalization with ozone and plasma treatments, would inevitably degrade the quality of the underlying graphene. Here, we tackled this problem by utilizing an effective and convenient physical method. In detail, the graphene surface was pretreated with the deposition of thermally evaporated ultrathin Al metal layer prior to the Al2O3 growth by ALD. Then the device was placed in a drying oven for 30 min to be naturally oxidized as a seed layer. With the assistance of an Al oxide seed layer, pinhole-free Al2O3 dielectrics growth on graphene was achieved. No detective defects or disorders were introduced into graphene by Raman characterization. Moreover, our fabricated graphene top-gated field effect transistor exhibited high mobility (∼6200 cm2V−1s−1) and high transconductance (∼117 μS). Thin dielectrics demonstrated a relative permittivity of 6.5 over a large area and a leakage current less than 1.6 pA/μm2. These results indicate that Al oxide functionalization is a promising pathway to achieve scaled gate dielectrics on graphene with high performance. [ABSTRACT FROM AUTHOR]

Published
2020
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9. A hybrid AR-DWT-EMD model for the short-term prediction of nonlinear and non-stationary ship motion

Author

Wu Wei, Qin Shi-qiao, and De-jun

Subjects
Engineering, Nonlinear autoregressive exogenous model, 010504 meteorology & atmospheric sciences, business.industry, 01 natural sciences, Ship motions, Hilbert–Huang transform, 010305 fluids & plasmas, Wavelet packet decomposition, Time–frequency analysis, Nonlinear system, Autoregressive model, Control theory, 0103 physical sciences, Time series, business, Simulation, 0105 earth and related environmental sciences
Abstract

Reliable and accurate short-term prediction of ship motions improves the safety in ship motion related maritime operations, where the empirical mode decomposition (EMD) is widely used for its advantages like the satisfactory nonlinear and non-stationary processing capability. Therefore a hybrid autoregressive AR-DWT-EMD model is proposed for the short-term prediction of non-stationary and nonlinear ship motion. The proposed hybrid model is the combination of AR-EMD model and the discrete wavelet decomposition (DWT). Compared with the traditional AR model, hybrid AR-DWT model, and hybrid AR-EMD model, the hybrid AR-DWT-EMD model is more capable to handle the nonlinear and non-stationary signals. The prediction results suggest that better predictions are obtained by the proposed AR-DWT-EMD model than other models.

Published
2016

11. Prediction of ship pitch motion by dual autoregressive model

Author

Zheng Jia-xing, Wu Wei, Wang Wei-chao, and Qin Shi-qiao

Subjects
Engineering, Heading (navigation), Autoregressive model, Control theory, business.industry, Work (physics), Response amplitude operator, Time series, business, Focus (optics), Hilbert–Huang transform, Motion (physics), Simulation
Abstract

We focus on the pitch motion prediction for the ship heading maneuver operation. A dual Autoregressive (AR) model is proposed to sensitively predict the ship pitch motion time series data, comparing to the tradition AR model, which is incapable of predicting the static component of the ship pitch motion time series data. Potential application of this work is establishing a superior real-time ship motion predict system.

Published
2015

20. Broadband single-layered graphene absorber using periodic arrays of graphene ribbons with gradient width

Author

Zhu Zhihong, Yuan Xiaodong, Liu Ken, Qin Shi-qiao, Guo Chucai, and Zhang Jianfa

Subjects
Materials science, Terahertz radiation, business.industry, Graphene, General Engineering, General Physics and Astronomy, Dielectric, law.invention, Wavelength, Optics, law, Broadband, Center frequency, business, Graphene nanoribbons, Plasmon
Abstract

We demonstrate that a broadband single-layered graphene absorber can be obtained in the THz range using periodic arrays of chemically doped graphene ribbons with gradient width, supported on a dielectric film placed on a thick piece of metal. The working bandwidth of 90% absorption for this structure is as high as 1.3 THz with a central frequency of 3 THz. The broadband operation mechanism is a result of the varying continuous plasmon resonances occurring in graphene ribbons with gradient width. The operation wavelength can be expanded to the far-infrared range.

Published
2014

28. Size Controlled Synthesis of 2-6 nm Gold Nanoparticles via Controlling Concentration of the Reducing Agent and Temperature

Author

Luo, Wei, Wang, Fei, Zhang, Xue Ao, Shao, Zheng Zheng, Fang, Jing Yue, Chang, Sheng Li, and Qin, Shi Qiao

Abstract

We reported a facile synthesis route for size controlled preparation of gold nanoparticles (Au NPs) by controlling concentration of the reducing agent and temperature. Nearly monodisperse Au NPs with mean diameters of 2-6 nm are acquired via the reduction of HAuCl4 by NaBH4 in the presence of tri-n-octyl amine and dodecanethiol in solvent of toluene. Results indicate that concentration of the reducing agent and temperature are key factors to tune the particle size and uniformity in the synthesis of Au NPs. The as-synthesized Au NPs show size dependent surface plasmonic properties between 510 and 525 nm, while Au NPs with size smaller than 3 nm do not clearly show the property.

Published
2012
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29. Controllable Extinction Property of Au/SiO2 Nanocomposite Induced by Neutralization Reaction Time

Author

Fang, Jing Yue, Zhang, Xue Ao, Qin, Shi Qiao, Wang, Fei, Li, Xin Hua, and Chang, Sheng Li

Abstract

The Au/SiO2 nanocomposite was produced using surface active agent P123, and its optical absorption spectra was measured by spectrophotometer. It was found that the intensity of absorption peak was strengthened and underwent a red-shift as the neutralization reaction time extended. The variation of optical extinction property of one gold particle (GP) with different size had been investigated by Mie theory. It was found that the extinction property of the single spherical GP possessed an obvious size effect. The extinction property of Au/SiO2 nanocomposite had been analyzed by Maxwell-Garnett (MG) theory. It showed that the extinction peak underwent a red-shift and the extinction intensity was strengthened when the size of gold nanoparticles (GNs) increased. The theoretical and the experimental results show that the extinction property of Au/SiO2 nanocomposite changes because the scattering effect of GNs are strengthened when their sizes increased by controlling the neutralization reaction time.

Published
2011
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31. Ultra-fast pulse propagation in nonlinear graphene/silicon ridge waveguide.

Author

Zhu, Zhi Hong, Qin, Shi Qiao, Liu, Ken, Zhang, Jian Fa, Xu, Wei, Guo, Chu Cai, and Li, Xiu Jian

Subjects
*FEMTOSECOND lasers, *COMPLEMENTARY metal oxide semiconductors, *GRAPHENE, *WAVEGUIDE lasers, *LIGHT absorption, *KERR electro-optical effect
Abstract

We report the femtosecond laser propagation in a hybrid graphene/silicon ridge waveguide with demonstration of the ultra-large Kerr coefficient of graphene. We also fabricated a slot-like graphene/silicon ridge waveguide which can enhance its effective Kerr coefficient 1.5 times compared with the graphene/silicon ridge waveguide. Both transverse-electric-like (TE-like) mode and transverse-magnetic-like (TM-like) mode are experimentally measured and numerically analyzed. The results show nonlinearity dependence on mode polarization not in graphene/silicon ridge waveguide but in slot-like graphene/silicon ridge waveguide. Great spectral broadening was observed due to self-phase modulation (SPM) after propagation in the hybrid waveguide with length of 2 mm. Power dependence property of the slot-like hybrid waveguide is also measured and numerically analyzed. The results also confirm the effective Kerr coefficient estimation of the hybrid structures. Spectral blue shift of the output pulse was observed in the slot-like graphene/silicon ridge waveguide. One possible explanation is that the blue shift was caused by the ultra-fast free carrier effect with the optical absorption of the doped graphene. This interesting effect can be used for soliton compression in femtosecond region. We also discussed the broadband anomalous dispersion of the Kerr coefficient of graphene. [ABSTRACT FROM AUTHOR]

Published
2015
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