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605 results on '"Shi Wangzhou"'

209. Interfacial and electrical characteristics of tetragonal HfO2/Al2O3 multilayer grown on AlGaN/GaN.

Author

Cao, Duo, Liu, Feng, Shi, Xi, Shi, Hui, Zheng, Li, Shen, Lingyan, Cheng, Xinhong, Yu, Yuehui, Li, Xiaolong, and Shi, Wangzhou

Subjects
ALUMINUM gallium nitride, HETEROSTRUCTURES, HETEROJUNCTIONS, ATOMIC layer deposition, CHEMICAL vapor deposition
Abstract

We report the study of HfO2/Al2O3 multilayer (HAOM) that is deposited on AlGaN/GaN heterostructure by plasma enhanced atomic layer deposition (PEALD). The properties and passivation effect of HAOM, sole Al2O3 and HfO2 films were investigated. After high-temperature rapid thermal annealing (RTA) of 850 °C, the formation of tetragonal phase in HAOM is presented. Al incorporates into HfO2 layers during RTA, which facilitates the formation of tetragonal HfO2. The HAOM film reveals an effective dielectric constant of ~ 30.2, a critical electric field of 7.6 MV/cm and leakage of only 6.8 × 10−4 mA/cm2 at gate bias of |Vg − Vfb| = 10 V. The HAOM insulating layer is shown to be effective in suppressing leakage current. In particular, the HAOM MIS diode current is reduced by both 6 orders of magnitude at negative bias of − 10 V and forward bias of 1.5 V compared with a conventional Schottky diode. [ABSTRACT FROM AUTHOR]

Published
2018
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210. Growth and electrical properties of epitaxial 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 thin film by pulsed laser deposition.

Author

Jiao, Shan, Tang, Yanxue, Zhao, Xiangyong, Wang, Tao, Duan, Zhihua, Wang, Feifei, Sun, Dazhi, Luo, Haosu, and Shi, Wangzhou

Subjects
PULSED laser deposition, THIN films, STRAY currents, FERROELECTRIC devices, HYSTERESIS loop, LEAD-free ceramics, FERROELECTRIC ceramics
Abstract

(100)-oriented epitaxial relaxor ferroelectric 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) thin film was prepared on SrRuO3-buffered SrTiO3 single-crystal substrate by pulsed laser deposition. The phase and domain structure, ferroelectric and piezoelectric properties, and leakage current behavior were studied. Results indicated well saturated polarization-versus-electric field hysteresis loops with large remnant polarization of 30 µC/cm2 and coercive field of 11 kV/mm was obtained. The analysis on the leakage current behavior proposed that linear ohmic conduction and Fowler-Nordheim tunneling were the dominant mechanism for the electric field amplitude below and above 15 kV/mm, respectively. Furthermore, the epitaxial PMN-0.3PT thin film exhibited excellent local piezoelectric response and in situ electric-field-induced domain switching behavior. These results suggest the potential applications of the present epitaxial PMN-0.3PT film in integrated ferroelectric devices. [ABSTRACT FROM AUTHOR]

Published
2018
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211. Pyroelectric properties of Mn‐doped Aurivillius ceramics with different pseudo‐perovskite layers.

Author

Tang, Yanxue, Shen, Zong‐Yang, Zhao, Xiangyong, Wang, Feifei, Shi, Wangzhou, Sun, Dazhi, Zhou, Zhiyong, and Zhang, Shujun

Subjects
PYROELECTRICITY, MANGANESE, DOPED semiconductors, CERAMIC materials, PEROVSKITE
Abstract

Abstract: The pyroelectric properties of Mn‐doped Aurivillius ceramics with different pseudo‐perovskite layers were investigated. The pyroelectric coefficients for 0.2 wt% Mn‐doped two‐layer CaBi2Nb2O9 (CBN–Mn), three‐layer Bi4Ti2.85Nb0.15O12 (BTN–Mn), and four‐layer CaBi4Ti3.95Nb0.05O15 (CBTN–Mn) ferroelectric ceramics were found to be on the order of 26.0, 54.4, 84.4 μC/m2K at room temperature, respectively. These values were closely associated with the number of octahedral layers in the pseudo‐perovskite blocks. The high pyroelectric coefficient, together with low dielectric permittivity and loss (tan δ < 0.003), results in to high figures of merit for the current responsivity, voltage responsivity, and detectivity. The excellent pyroelectric properties and high Curie temperatures (TC > 660°C) make the Aurivillius ceramics potential candidates for pyroelectric devices over a broad temperature range. [ABSTRACT FROM AUTHOR]

Published
2018
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227. The study of structural characteristics of YBaCuO superconducting thin films on (001) Zr(Y)O2by x‐ray diffraction

Author

Zhou Guien, Qi Zhenzhong, Jia Yunbo, Shi Jianzhong, Lu Jiang, Huang Yunlan, Yao Weiguo, Shi Wangzhou, and Zhang Yuheng

Subjects
Diffraction, Crystallography, Materials science, Sputtering, Transmission electron microscopy, X-ray crystallography, General Physics and Astronomy, Mineralogy, Crystal growth, Substrate (electronics), Thin film, Epitaxy
Abstract

Three kinds of x‐ray diffraction experiment of YBa2Cu3O7−x thin film on Zr(Y)O2 have been carried out. It has been proved that YBaCuO superconducting thin film grow epitaxially on (001) Zr(Y)O2. The orientation relationships between YBaCuO thin film and Zr(Y)O2 substrate are (001) YBaCuO∥(001) ZrO2 and [100] YBaCu∥[110] Zr(Y)O2.

Published
1991
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228. In situ reversible tuning of photoluminescence of an epitaxial thin film via piezoelectric strain induced by a Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal.

Author

Wang, Feifei, Liu, Dan, Chen, Zibin, Duan, Zhihua, Zhang, Yi, Sun, Dazhi, Zhao, Xiangyong, Shi, Wangzhou, Zheng, Renkui, and Luo, Haosu

Abstract

Conventionally, photoluminescence (PL) properties are mainly modulated through traditional chemical approaches which are ex situ, irreversible and static modulation techniques, potentially limiting the understanding of the detailed process of luminescence and smart PL applications. Here, an in situ dynamic routine is developed to tune the PL response in an epitaxial Yb3+/Er3+ co-doped BaTiO3 thin film through electric-field-induced strain of a piezoelectric single-crystal Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) substrate. A reversible tuning and enhancement of the PL intensity was achieved when an external electric field was applied to the PMN–PT single-crystal substrate. The underlying mechanism responsible for the dynamic enhancement of the PL intensity was attributed to the strain induced lower host symmetry so as to enhance the hypersensitive transition probability of the rare-earth ions. The present work could provide a significant guide for the in situ dynamic and active modulation of the PL performances of luminescent devices through the piezoelectric strain. [ABSTRACT FROM AUTHOR]

Published
2017
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241. Effect of additional silicon on titanium/4H-SiC contacts properties

Author

Tan Jiahui, Zhang Yongping, Shi Wangzhou, Zhi-zhan Chen, Cheng Yue, and Lu Wuyue

Subjects
Materials science, chemistry, X-ray photoelectron spectroscopy, Silicon, Scanning electron microscope, Annealing (metallurgy), Electrode, General Physics and Astronomy, chemistry.chemical_element, Composite material, Sputter deposition, Ohmic contact, Titanium
Abstract

The Ti electrode was deposited on the (000) face of an n-type 4H-SiC substrate by magnetron sputtering. The effect of the electrode placement method during the annealing treatment on the contact property was carefully investigated. When the electrode was faced to the Si tray and annealed, it showed ohmic behavior, otherwise it showed a non-ohmic property. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to characterize the electrode phase, composition, thickness, and surface morphology. The additional silicon introduced from the Si tray played a key role in the formation of the ohmic contact on the Ti/4H-SiC contact.

Published
2014
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242. Hall Effect of an Oriented Superconducting YBa 2 Cu 3 O y Film

Author

Cheng Xiang-Ai, Zhou Guien, Sha Jian, QI Zhenzhong, Yao Weiguo, Wang Shunxi, HE Zhen-Hui, Shi Wangzhou, and Zhang Qirui

Subjects
Superconductivity, Materials science, Micrograph, Condensed matter physics, Hall effect, Scanning electron microscope, Condensed Matter::Superconductivity, Thermal Hall effect, General Physics and Astronomy, Grain boundary, Thin film, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Magnetic field
Abstract

A superconducting YBa2Cu3Oy thin film, which is well oriented at (001) direction and in which no grain boundary is observed in the resolution limit of scanning electron microscope micrograph, is selected for the Hall effect measurement from 80 to 220 K under a magnetic field of 3 T. A very narrow and negative peak of the Hall voltage (VH) is found in the superconducting transition region. A linear dependence of the carrier concentration (nH) on temperature is found in the normal state. The appearance of such a negative peak is attributed to the intrinsic anisotropy of the Hall coefficient (RH) related to the direction of the applied field and current.

Published
1991
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