116 results on '"Gang Wang"'
Search Results
2. Analysis of high-temperature performance of 4H-SiC avalanche photodiodes in both linear and Geiger modes
- Author
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Xing-Ye Zhou, Yuan-Jie Lv, Hong-Yu Guo, Guo-Dong Gu, Yuan-Gang Wang, Shi-Xiong Liang, Ai-Min Bu, and Zhi-Hong Feng
- Subjects
General Physics and Astronomy - Abstract
The high-temperature performance of 4H-SiC ultraviolet avalanche photodiodes (APDs) in both linear and Geiger modes is extensively investigated. During the temperature-dependent measurements, a fixed bias voltage is adopted for the device samples, which is much more practical and important for high-temperature applications. The results show that the fabricated 4H-SiC APDs are very stable and reliable at high temperatures. As the temperature increases from room temperature to 425 K, the dark current at 95% of the breakdown voltage increases slightly and remains lower than 40 pA. In Geiger mode, our 4H-SiC APDs can be self-quenched in a passive-quenching circuit, which is expected for high-speed detection systems. Moreover, an interesting phenomenon is observed for the first time: the single-photon detection efficiency shows a non-monotonic variation as a function of temperature. The physical mechanism of the variation in high-temperature performance is further analyzed. The results in this work can provide a fundamental reference for researchers in the field of 4H-SiC APD ultraviolet detectors.
- Published
- 2023
3. Generation of elliptical airy vortex beams based on all-dielectric metasurface
- Author
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Xiao-Ju Xue, Bi-Jun Xu, Bai-Rui Wu, Xiao-Gang Wang, Xin-Ning Yu, Lu Lin, and Hong-Qiang Li
- Subjects
General Physics and Astronomy - Abstract
Elliptical airy vortex beams (EAVBs) can spontaneously form easily identifiable topological charge focal spots. They are used for topological charge detection of vortex beams because they have the abruptly autofocusing properties of circular airy vortex beams and exhibit unique propagation characteristics. We study the use of the dynamic phase and Pancharatnam–Berry phase principles for generation and modulation of EAVBs by designing complex-amplitude metasurface and phase-only metasurface, at an operating wavelength of 1500 nm. It is found that the focusing pattern of EAVBs in the autofocusing plane splits into |m|+1 tilted bright spots from the original ring, and the tilted direction is related to the sign of the topological charge number m. Due to the advantages of ultra-thin, ultra-light, and small size of the metasurface, our designed metasurface device has potential applications in improving the channel capacity based on orbital angular momentum communication, information coding, and particle capture compared to spatial light modulation systems that generate EAVBs.
- Published
- 2023
4. Deep-learning-based cryptanalysis of two types of nonlinear optical cryptosystems
- Author
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Xiao-Gang Wang and Hao-Yu Wei
- Subjects
General Physics and Astronomy - Abstract
The two types of nonlinear optical cryptosystems (NOCs) that are respectively based on amplitude-phase retrieval algorithm (APRA) and phase retrieval algorithm (PRA) have attracted a lot of attention due to their unique mechanism of encryption process and remarkable ability to resist common attacks. In this paper, the securities of the two types of NOCs are evaluated by using a deep-learning (DL) method, where an end-to-end densely connected convolutional network (DenseNet) model for cryptanalysis is developed. The proposed DL-based method is able to retrieve unknown plaintexts from the given ciphertexts by using the trained DenseNet model without prior knowledge of any public or private key. The results of numerical experiments with the DenseNet model clearly demonstrate the validity and good performance of the proposed the DL-based attack on NOCs.
- Published
- 2022
5. Investigation of the structural and dynamic basis of kinesin dissociation from microtubule by atomistic molecular dynamics simulations
- Author
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Jian-Gang Wang, Xiao-Xuan Shi, Yu-Ru Liu, Peng-Ye Wang, Hong Chen, and Ping Xie
- Subjects
General Physics and Astronomy ,macromolecular substances - Abstract
Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules. An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtubule. Here, using all-atom molecular dynamics simulations, we studied the dissociation process of the kinesin head in weak-microtubule-binding or ADP state from tubulin on the basis of the available high-resolution structural data for the head and tubulin. By analyzing the simulated snapshots of the structure of the head-tubulin complex we provided detailed structural and dynamic information for the dissociation process. We found that the dissociation of the head along different directions relative to the tubulin exhibits very different dynamic behaviors. Moreover, the potential forms or energy landscapes of the interaction between the head and tubulin along different directions were determined. The studies have important implications for the detailed molecular mechanism of the dissociation of the kinesin motor and thus are critical to the mechanism of its processivity.
- Published
- 2022
6. Modeling of high permittivity insulator structure with interface charge by charge compensation
- Author
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Zhi-Gang Wang, Zhuang Liu, and Yun-Feng Gong
- Subjects
Materials science ,Condensed matter physics ,Interface (Java) ,General Physics and Astronomy ,Charge (physics) ,Charge compensation - Abstract
An analytical model of the power metal–oxide–semiconductor field-effect transistor (MOSFET) with high permittivity insulator structure (HKMOS) with interface charge is established based on superposition and developed for optimization by charge compensation. In light of charge compensation, the disturbance aroused by interface charge is efficiently compromised by introducing extra charge for maximizing breakdown voltage (BV) and minimizing specific ON-resistance (R on,sp). From this optimization method, it is very efficient to obtain the design parameters to overcome the difficulty in implementing the R on,sp–BV trade-off for quick design. The analytical results prove that in the HKMOS with positive or negative interface charge at a given length of drift region, the extraction of the parameters is qualitatively and quantitatively optimized for trading off BV and R on,sp with JFET effect taken into account.
- Published
- 2021
7. A fitting formula for electron–ion energy partition fraction of 3.54-MeV fusion alpha particles in hot dense deuterium–tritium plasmas*
- Author
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Zhi-Gang Wang, Yongtao Zhao, Bin He, and Yan-Ning Zhang
- Subjects
Fusion ,Materials science ,Deuterium ,General Physics and Astronomy ,Partition (number theory) ,Tritium ,Electron ,Plasma ,Alpha particle ,Atomic physics ,Inertial confinement fusion - Abstract
Based on our previous work (Phys. Plasmas 25 012704 (2018)), a fitting formula is given for electron–ion energy partition fraction of 3.54-MeV fusion alpha particles in deuterium–tritium (DT) plasmas as a function of plasma mass density ρ, electron temperature T e, and ion temperature T i. The formula can be used in a huge range of the plasma state, where ρ varies between 1.0 g/cc ∼ 10.03 g/cc and both T e and T i change from 0.1 keV to 100.0 keV. Relativistic effect for electrons is investigated including the effect of the projectile recoil in the plasmas at T e ≥ 50.0 keV. The partition fraction for T e > T i is found to be close to that for T e = T i. The comparisons with other fitting results are made at some plasma densities when T e = T i, and the difference is explained. The fitting result is very close to the calculated one in most cases, which is convenient for the simulation of alpha heating in hot dense DT plasmas for inertial confined fusion.
- Published
- 2021
8. PBTI stress-induced 1/f noise in n-channel FinFET*
- Author
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Gang Wang, Jin-Shun Bi, Dan-Yang Chen, and Kai Xi
- Subjects
Noise ,Materials science ,Acoustics ,Stress induced ,N channel ,General Physics and Astronomy - Abstract
The influence of positive bias temperature instability (PBTI) on 1 / f noise performance is systematically investigated on n-channel fin field-effect transistor (FinFET). The FinFET with long and short channel (L = 240 nm, 16 nm respectively) is characterized under PBTI stress from 0 s to 104 s. The 1 / f noise features are analyzed by using the unified physical model taking into account the contributions from the carrier number and channel mobility fluctuations. The I d–V g, I d–V d, I g–V g tests are conducted to support and verify the physical analysis in the PBTI process. It is found that the influence of the channel mobility fluctuations may not be neglected. Due to the mobility degradation in a short-channel device, the noise level of the short channel device also degrades. Trapping and trap generation regimes of PBTI occur in high-k layer and are identified based on the results obtained for the gate leakage current and 1 / f noise.
- Published
- 2020
9. Theoretical insights into photochemical ESITP process for novel DMP-HBT-py compound*
- Author
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Guang Yang, Kaifeng Chen, Dapeng Yang, and Gang Wang
- Subjects
Materials science ,Scientific method ,Heterojunction bipolar transistor ,General Physics and Astronomy ,Excited state intramolecular proton transfer ,Photochemistry - Abstract
We execute the density functional theory (DFT) and time-dependent density functional theory (TDDFT) approaches to make a detailed exploration about excited state luminescent properties as well as excited state intramolecular proton transfer (ESIPT) mechanism for the novel 2,6-dimethyl phenyl (DMP-HBT-py) system. Firstly, we check and confirm the formation and stabilization of hydrogen bonding interaction for DMP-HBT-py. Via optimized geometrical parameters of primary chemical bond and infrared (IR) spectra, we find O–H⋯N hydrogen bond of DMP-HBT-py should be strengthened in S1 state. Insights into frontier molecular orbitals (MOs) analyses, we infer charge redistribution and charge transfer (ICT) phenomena motivate ESIPT trend. Via probing into potential energy curves (PECs) in related electronic states, we come up with the ultrafast ESIPT behavior due to low potential barrier. Furthermore, we search the reaction transition state (TS) structure, the ultrafast ESIPT behavior and mechanism of DMP-HBT-py compound can be re-confirmed. We sincerely wish this work could play roles in further developing novel applications based on DMP-HBT-py compound and in promoting efficient solid emitters in OLEDs in future.
- Published
- 2020
10. Band alignment of p-type oxide/ε-Ga2O3 heterojunctions investigated by x-ray photoelectron spectroscopy*
- Author
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Chen Weiqu, Yanli Pei, Zeyuan Fei, Zimin Chen, Jun Liang, Chang Rao, Gang Wang, Xinzhong Wang, and Xing Lu
- Subjects
chemistry.chemical_compound ,Crystallography ,Materials science ,chemistry ,X-ray photoelectron spectroscopy ,Oxide ,General Physics and Astronomy ,Heterojunction - Abstract
The ε-Ga2O3 p–n heterojunctions (HJ) have been demonstrated using typical p-type oxide semiconductors (NiO or SnO). The ε-Ga2O3 thin film was heteroepitaxial grown by metal organic chemical vapor deposition (MOCVD) with three-step growth method. The polycrystalline SnO and NiO thin films were deposited on the ε-Ga2O3 thin film by electron-beam evaporation and thermal oxidation, respectively. The valence band offsets (VBO) were determined by x-ray photoelectron spectroscopy (XPS) to be 2.17 eV at SnO/ε-Ga2O3 and 1.7 eV at NiO/ε-Ga2O3. Considering the bandgaps determined by ultraviolet-visible spectroscopy, the conduction band offsets (CBO) of 0.11 eV at SnO/ε-Ga2O3 and 0.44 eV at NiO/ε-Ga2O3 were obtained. The type-II band diagrams have been drawn for both p–n HJs. The results are useful to understand the electronic structures at the ε-Ga2O3 p–n HJ interface, and design optoelectronic devices based on ε-Ga2O3 with novel functionality and improved performance.
- Published
- 2020
11. Irradiation study of liquid crystal variable retarder for Full-disk Magneto-Graph payload onboard ASO-S mission*
- Author
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Jun-Feng Hou, Yuanyong Deng, Dong-Guang Wang, Hong-Wei Li, Hai-Feng Wang, Gang Wang, Yong-Quan Luo, and Zhen-Long Zhang
- Subjects
Physics ,Variable (computer science) ,Optics ,Liquid crystal ,business.industry ,Payload ,General Physics and Astronomy ,Graph (abstract data type) ,Irradiation ,business ,Retarder ,Magneto ,Solar telescope - Abstract
The Advanced Space-based Solar Observatory (ASO-S) is a mission proposed by the Chinese Solar Physics Community. As one of the three payloads of ASO-S, the Full-disc Magneto-Graph (FMG) will measure the photospheric magnetic fields of the entire solar disk with high spatial and temporal resolution, and high magnetic sensitivity, where liquid crystal variable retarder (LCVR) is the key to whether FMG can achieve its scientific goal. So far, there is no space flight experience for LCVR. Therefore, irradiation study for LCVRs becomes more important and urgent in order to make sure their safety and reliability in space application. In this paper, λ irradiation, proton irradiation, and ultra-violet (UV) irradiation are tested for LCVRs respectively. The optical and chemical properties during irradiation tests are measured and analyzed. For optical properties, there is no significant change in those parameters FMG payload concerned except the retardation. Although there is no drastic degradation in the retardation versus voltage during irradiations, the amount of retardation variation is much higher than the instrument requirements. Thus, an in-flight retardation versus voltage should be added in FMG payload, reducing or even avoiding the impact of retardation change. For chemical properties, the clearing point and birefringence of the LC materials almost have no change; the ion density dose not change below 60 krad[Si], but begin to increase dramatically above 60 krad[Si].
- Published
- 2020
12. Modeling electric field of power metal-oxide-semiconductor field-effect transistor with dielectric trench based on Schwarz–Christoffel transformation*
- Author
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Zhi-Gang Wang, Ya-Nan Wang, and Tao Liao
- Subjects
Christoffel symbols ,Materials science ,business.industry ,General Physics and Astronomy ,Conformal map ,Dielectric ,Condensed Matter::Materials Science ,Transformation (function) ,Electric field ,Trench ,Optoelectronics ,Breakdown voltage ,Field-effect transistor ,business - Abstract
A power metal-oxide-semiconductor field-effect transistor (MOSFET) with dielectric trench is investigated to enhance the reversed blocking capability. The dielectric trench with a low permittivity to reduce the electric field at reversed blocking state has been studied. To analyze the electric field, the drift region is segmented into four regions, where the conformal mapping method based on Schwarz–Christoffel transformation has been applied. According to the analysis, the improvement in the electric field for using the low permittivity trench is mainly due to the two electric field peaks generated in the drift region around this dielectric trench. The analytical results of the electric field and the potential models are in good agreement with the simulation results.
- Published
- 2019
13. Head-on collision between two solitary waves in a one-dimensional bead chain
- Author
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Fu-Gang Wang, Juan-Fang Han, Wen-Shan Duan, and Yang Yangyang
- Subjects
Physics ,Bead (woodworking) ,Chain (algebraic topology) ,0103 physical sciences ,General Physics and Astronomy ,010306 general physics ,01 natural sciences ,Molecular physics ,010305 fluids & plasmas ,Head-on collision - Published
- 2018
14. Segregations and desorptions of Ge atoms in nanocomposite Si 1− x Ge x films during high-temperature annealing
- Author
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Youdou Zheng, Gang Wang, Ze-Wen Zou, Yu Wang, Meng Yang, Yun Li, Xiaoxu Wei, Junzhuan Wang, and Yi Shi
- Subjects
010302 applied physics ,Materials science ,Nanocomposite ,Annealing (metallurgy) ,Analytical chemistry ,General Physics and Astronomy ,02 engineering and technology ,Chemical vapor deposition ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Nanocrystal ,law ,Desorption ,0103 physical sciences ,Melting point ,Inductively coupled plasma ,Crystallization ,0210 nano-technology - Abstract
Nanocomposite Si1−x Ge x films are deposited by dual-source jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD). The segregations and desorptions of Ge atoms, which dominate the structural evolutions of the films during high-temperature annealing, are investigated. When the annealing temperature ( is 900 °, the nanocomposite Si1−x Ge x films are well crystallized, and nanocrystals (NCs) with the core-shell structure form in the films. After being annealed at 1000 °C (above the melting point of bulk Ge), Ge atoms accumulate on the surfaces of Ge-rich films, whereas pits appear on films with lower Ge content, resulting from desorption. Meanwhile, voids are observed in the films. A cone-like structure involving the percolation of the homogeneous clusters and the crystallization of NCs enhances Ge segregation.
- Published
- 2017
15. Band structure of silicon and germanium thin films based on first principles
- Author
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Zhong-Mei Huang, Tai-Ge Dong, Gang Wang, Chao-Jian Qin, Wei-Qi Huang, Xue-Ke Wu, and Yan-Lin Tang
- Subjects
Materials science ,Silicon ,business.industry ,Band gap ,General Physics and Astronomy ,chemistry.chemical_element ,Nanotechnology ,Germanium ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanomaterials ,chemistry ,Quantum dot ,0103 physical sciences ,Optoelectronics ,Density functional theory ,Thin film ,010306 general physics ,0210 nano-technology ,Electronic band structure ,business - Abstract
In nanomaterials, optical anisotropies reveal a fundamental relationship between structural and optical properties, in which directional optical properties can be exploited to enhance the performance of optoelectronic devices. First principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA) are carried out to investigate the energy band gap structure on silicon (Si) and germanium (Ge) nanofilms. Simulation results show that the band gaps in Si (100) and Ge (111) nanofilms become the direct-gap structure in the thickness range less than 7.64 nm and 7.25 nm respectively, but the band gaps of Si (111) and Ge (110) nanofilms still keep in an indirect-gap structure and are independent on film thickness, and the band gaps of Si (110) and Ge (100) nanofilms could be transferred into the direct-gap structure in nanofilms with smaller thickness. It is amazing that the band gaps of Si sandwich structure become the direct-gap structure in a certain area whether (111) or (100) surface. The band structure change of Si and Ge thin films in three orientations is not the same and the physical mechanism is very interesting, where the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects.
- Published
- 2017
16. High-performance InGaN/GaN MQW LEDs with Al-doped ZnO transparent conductive layers grown by MOCVD using H 2 O as an oxidizer
- Author
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Yanli Pei, Ruiqin Hu, Jiayong Lin, Guangshuo Cai, Gang Wang, Zimin Chen, and Yi Zhuo
- Subjects
010302 applied physics ,Materials science ,business.industry ,Annealing (metallurgy) ,Doping ,General Physics and Astronomy ,02 engineering and technology ,Chemical vapor deposition ,01 natural sciences ,Indium tin oxide ,law.invention ,020210 optoelectronics & photonics ,law ,Electrical resistivity and conductivity ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Optoelectronics ,Metalorganic vapour phase epitaxy ,business ,Diode ,Light-emitting diode - Abstract
In this study, the high performance of InGaN/GaN multiple quantum well light-emitting diodes (LEDs) with Al-doped ZnO (AZO) transparent conductive layers (TCLs) has been demonstrated. The AZO-TCLs were fabricated on the n+-InGaN contact layer by metal organic chemical vapor deposition (MOCVD) using H2O as an oxidizer at temperatures as low as 400 °C without any post-deposition annealing. It shows a high transparency (98%), low resistivity (510−4 Ωcm), and an epitaxial-like excellent interface on p-GaN with an n+-InGaN contact layer. A forward voltage of 2.82 V @ 20 mA was obtained. Most importantly, the power efficiencies can be markedly improved by 53.8%@20 mA current injection and 39.6%@350 mA current injection compared with conventional LEDs with indium tin oxide TCL (LED-III), and by 28.8%@20 mA current injection and 4.92%@350 mA current injection compared with LEDs with AZO-TCL prepared by MOCVD using O2 as an oxidizer (LED-II), respectively. The results indicate that the AZO-TCL grown by MOCVD using H2O as an oxidizer is a promising TCL for a low-cost and high-efficiency GaN-based LED application.
- Published
- 2016
17. Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO 2 on Al-doped ZnO transparent conductive layer
- Author
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Gang Wang, Zhen Liu, Yu Zhao, Yiting Chen, Bingfeng Fan, Yi Zhuo, and Zhoujun Pang
- Subjects
010302 applied physics ,Materials science ,business.industry ,Doping ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Planar ,Etching (microfabrication) ,law ,0103 physical sciences ,Electrode ,Optoelectronics ,0210 nano-technology ,business ,Electrical conductor ,Layer (electronics) ,Diode ,Light-emitting diode - Abstract
We report an effective enhancement in light extraction of GaN-based light-emitting diodes (LEDs) with an Al-doped ZnO (AZO) transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent through-pore anodic aluminum oxide (AAO) membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 mA and 56% at 100 mA compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.
- Published
- 2016
18. Spectral broadening induced by intense ultra-short pulse in 4H–SiC crystals
- Author
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Gang Wang, Chunhua Xu, Teng-fei Yan, Xiaolong Chen, Wenjun Wang, and Jingkui Liang
- Subjects
Materials science ,business.industry ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Spectral line ,law.invention ,010309 optics ,Full width at half maximum ,Optics ,law ,0103 physical sciences ,Atomic physics ,0210 nano-technology ,business ,Self-phase modulation ,Homogeneous broadening ,Refractive index ,Power density ,Doppler broadening - Abstract
© 2016 Chinese Physical Society and IOP Publishing Ltd. We report the observation of spectral broadening induced by 200 femtosecond laser pulses with the repetition rate of 1 kHz at the wavelength of 532 nm in semi-insulating 4H-SiC single crystals. It is demonstrated that the full width at half maximum of output spectrum increases linearly with the light propagation length and the peak power density, reaching a maximum 870 cm -1 on a crystal of 19 mm long under an incident laser with a peak power density of 60.1 GW/cm 2 . Such spectral broadening can be well explained by the self-phase modulation model which correlates time-dependent phase change of pulses to intensity-dependent refractive index. The nonlinear refractive index n 2 is estimated to be 1.88×10 -15 cm 2 /W. The intensity-dependent refractive index is probably due to both the nonlinear optical polarizability of the bound electrons and the increase of free electrons induced by the two-photon absorption process. Super continuum spectra could arise as crystals are long enough to induce the self-focusing effect. The results show that SiC crystals may find applications in spectral broadening of high power lasers.
- Published
- 2016
19. Wave propagation in beams with anti-symmetric piezoelectric shunting arrays
- Author
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Shengbing Chen and Gang Wang
- Subjects
Physics ,Wave propagation ,Acoustics ,Attenuation ,Transfer-matrix method (optics) ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Piezoelectricity ,Finite element method ,Vibration isolation ,0103 physical sciences ,Physics::Accelerator Physics ,010306 general physics ,0210 nano-technology ,Beam (structure) ,Longitudinal wave - Abstract
Piezoelectric shunting arrays are employed to control the wave propagation in flexible beams. Contrary to conventional symmetric configuration, a substrate beam with anti-symmetric shunting arrays is investigated by adapted transfer matrix method. Compared with symmetric scheme, the anti-symmetric one demonstrates some distinctive characteristics. Primarily, the longitudinal and flexural waves are coupled, so they are correlated and must be considered simultaneously. Moreover, the attenuation of flexural wave is much stronger in anti-symmetric scenario, while the longitudinal wave demonstrates the converse side. As a result, the anti-symmetric scheme can be utilized to improve the vibration isolation capability of shunting arrays. Finally, the theoretical analyses are validated by finite element simulations.
- Published
- 2016
20. Plasma induced by pulsed laser and fabrication of silicon nanostructures
- Author
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Quan Lv, Tai-Ge Dong, Gang Wang, Xin-Jian Miao, Zhong-Mei Huang, Wei-Qi Hang, Liu Shi-Rong Liu, and Chao-Jian Qin
- Subjects
Ytterbium ,Photoluminescence ,Materials science ,Silicon ,business.industry ,Band gap ,Physics::Optics ,General Physics and Astronomy ,chemistry.chemical_element ,Electroluminescence ,Wigner crystal ,chemistry ,Optoelectronics ,Spectroscopy ,business ,Plasmon - Abstract
It is interesting that in preparing process of nanosilicon by pulsed laser, the periodic diffraction pattern from plasmonic lattice structure in the Purcell cavity due to interaction between plasmons and photons is observed. This kind of plasmonic lattice structure confined in the cavity may be similar to the Wigner crystal structure. Emission manipulation on Si nanostructures fabricated by the plasmonic wave induced from pulsed laser is studied by using photoluminescence spectroscopy. The electronic localized states and surface bonding are characterized by several emission bands peaked near 600 nm and 700 nm on samples prepared in oxygen or nitrogen environment. The electroluminescence wavelength is measured in the telecom window on silicon film coated by ytterbium. The enhanced emission originates from surface localized states in band gap due to broken symmetry from some bonds on surface bulges produced by plasmonic wave in the cavity.
- Published
- 2015
21. A meshless scheme for partial differential equations based on multiquadric trigonometric B-spline quasi-interpolation
- Author
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Zhi-Gang Wang and Wen-Wu Gao
- Subjects
Regularized meshless method ,Partial differential equation ,Collocation ,B-spline ,General Physics and Astronomy ,Applied mathematics ,Boundary value problem ,Trigonometry ,System of linear equations ,Mathematics::Numerical Analysis ,Mathematics ,Interpolation - Abstract
Based on the multiquadric trigonometric B-spline quasi-interpolant, this paper proposes a meshless scheme for some partial differential equations whose solutions are periodic with respect to the spatial variable. This scheme takes into account the periodicity of the analytic solution by using derivatives of a periodic quasi-interpolant (multiquadric trigonometric B-spline quasi-interpolant) to approximate the spatial derivatives of the equations. Thus, it overcomes the difficulties of the previous schemes based on quasi-interpolation (requiring some additional boundary conditions and yielding unwanted high-order discontinuous points at the boundaries in the spatial domain). Moreover, the scheme also overcomes the difficulty of the meshless collocation methods (i.e., yielding a notorious ill-conditioned linear system of equations for large collocation points). The numerical examples that are presented at the end of the paper show that the scheme provides excellent approximations to the analytic solutions.
- Published
- 2014
22. Direct growth of graphene on gallium nitride by using chemical vapor deposition without extra catalyst
- Author
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Minjiang Chen, Gang Wang, Yun Zhao, Jiankun Yang, Fang Yu, Lianfeng Sun, Tongbo Wei, Ruifei Duan, Tie-Lei An, Li Tao, and Huaichao Yang
- Subjects
Materials science ,business.industry ,Graphene ,Graphene foam ,General Physics and Astronomy ,Gallium nitride ,Nanotechnology ,Chemical vapor deposition ,Nitride ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Optoelectronics ,Thin film ,business ,Graphene nanoribbons ,Graphene oxide paper - Abstract
Graphene on gallium nitride (GaN) will be quite useful when the graphene is used as transparent electrodes to improve the performance of gallium nitride devices. In this work, we report the direct synthesis of graphene on GaN without an extra catalyst by chemical vapor deposition. Raman spectra indicate that the graphene films are uniform and about 5–6 layers in thickness. Meanwhile, the effects of growth temperatures on the growth of graphene films are systematically studied, of which 950 °C is found to be the optimum growth temperature. The sheet resistance of the grown graphene is 41.1 Ω/square, which is close to the lowest sheet resistance of transferred graphene reported. The mechanism of graphene growth on GaN is proposed and discussed in detail. XRD spectra and photoluminescence spectra indicate that the quality of GaN epi-layers will not be affected after the growth of graphene.
- Published
- 2014
23. Dynamic surface wettability of three-dimensional graphene foam
- Author
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Ya Deng, Gang Wang, Guanglong Wang, Fengqi Gao, Wenbin Huang, Li Tao, Lianfeng Sun, Minjiang Chen, and Zhongtao Qiao
- Subjects
Materials science ,Graphene ,Scanning electron microscope ,Bilayer ,Graphene foam ,General Physics and Astronomy ,law.invention ,Contact angle ,symbols.namesake ,Chemical engineering ,law ,Monolayer ,symbols ,Wetting ,Raman spectroscopy - Abstract
In this work, three-dimensional graphene foams (GFs) are synthesized and characterized by scanning electron microscope (SEM) and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel (Ni) foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are ~ 58%, ~ 32%, ~ 8%, and ~ 2%, respectively. The contact angle (CA) (~ 12°) of water droplet (3 μL) on GF is found to be larger than that on Ni foam (~ 107°), indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets.
- Published
- 2014
24. Out-of-plane shear flow effects on fast magnetic reconnection in a two-dimensional hybrid simulation model
- Author
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Lin Wang, Xian-Qu Wang, Xiao-Gang Wang, and Yue Liu
- Subjects
Physics ,Antisymmetric relation ,General Physics and Astronomy ,Magnetic reconnection ,Mechanics ,Magnetic field ,Physics::Fluid Dynamics ,Shear (sheet metal) ,Out of plane ,Classical mechanics ,Physics::Space Physics ,Growth rate ,Shear flow ,Hybrid model - Abstract
The effects of out-of-plane shear flows on fast magnetic reconnection are numerically investigated by a two-dimensional (2D) hybrid model in an initial Harris sheet equilibrium with flows. The equilibrium and driven shear flows out of the 2D reconnection plane with symmetric and antisymmetric profiles respectively are used in the simulation. It is found that the out-of-plane flows with shears in-plane can change the quadrupolar structure of the out-of-plane magnetic field and, therefore, modify the growth rate of magnetic reconnection. Furthermore, the driven flow varying along the anti-parallel magnetic field can either enhance or reduce the reconnection rate as the direction of flow changes. Secondary islands are also generated in the process with converting the initial X-point into an O-point.
- Published
- 2014
25. Exploring FeSe-based superconductors by liquid ammonia method
- Author
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Xiaolong Chen, Gang Wang, Shifeng Jin, Tianping Ying, Shijie Shen, Han Zhang, Xiaofang Lai, Tingting Zhou, and Wanyan Wang
- Subjects
Superconductivity ,Iron-based superconductor ,Materials science ,Condensed matter physics ,chemistry ,Potassium ,Liquid ammonia ,General Physics and Astronomy ,chemistry.chemical_element - Abstract
Our recent progress on the preparation of a series of new FeSe-based superconductors and the clarification of SC phases in potassium-intercalated iron selenides are reviewed here. By the liquid ammonia method, metals Li, Na, Ca, Sr, Ba, Eu, and Yb are intercalated in between FeSe layers and form superconductors with transition temperatures of 30 K~46 K, which cannot be obtained by high-temperature routes. In the potassium-intercalated iron selenides, we demonstrate that at least two SC phases exist, KxFe2Se2(NH3)y (x ≈ 0.3 and 0.6), determined mainly by the concentration of potassium. NH3 has little, if any, effect on superconductivity, but plays an important role in stabilizing the structures. All these results provide a new starting point for studying the intrinsic properties of this family of superconductors, especially for their particular electronic structures.
- Published
- 2013
26. Lead zirconate titanate behaviors in an LDMOS
- Author
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Ping Li, Bin Hu, Weirong Huo, Junhong Li, Gang Wang, Xue Fan, Wei Li, and Yahong Zhai
- Subjects
LDMOS ,Materials science ,business.industry ,General Physics and Astronomy ,Hardware_PERFORMANCEANDRELIABILITY ,Dielectric ,Lead zirconate titanate ,Gate voltage ,Power (physics) ,chemistry.chemical_compound ,chemistry ,Hardware_INTEGRATEDCIRCUITS ,Energy transformation ,Optoelectronics ,business ,Electronic circuit ,Voltage - Abstract
The behaviors of lead zirconate titanate (PZT) deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current?gate voltage (ID?VG) memory window of about 2.2 V is obtained at the sweep voltages of ?10 V for the 350-V laterally diffused metal oxide semiconductor (LDMOS). The retention time of about 270 s is recorded for the LDMOS through a controlled ID?VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.
- Published
- 2013
27. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos
- Author
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Xisen Wen, Shengbing Chen, Jihong Wen, and Gang Wang
- Subjects
Physics ,business.industry ,Band gap ,Acoustics ,Physics::Optics ,General Physics and Astronomy ,Metamaterial ,Inductor ,Piezoelectricity ,Finite element method ,Vibration ,Optics ,Dispersion relation ,Dispersion (optics) ,business - Abstract
Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches.
- Published
- 2013
28. Orbit optimization for ASTROD-GW and its time delay interferometry with two arms using CGC ephemeris
- Author
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Gang Wang and Wei-Tou Ni
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Spacecraft ,business.industry ,FOS: Physical sciences ,General Physics and Astronomy ,Lagrangian point ,General Relativity and Quantum Cosmology (gr-qc) ,Ephemeris ,General Relativity and Quantum Cosmology ,symbols.namesake ,Interferometry ,Optical path ,Optics ,Physics::Space Physics ,symbols ,Orbit (dynamics) ,Astrophysics::Earth and Planetary Astrophysics ,business ,Doppler effect ,Noise (radio) ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitation Wave detection) is an optimization of ASTROD to focus on the goal of detection of gravitation waves. The detection sensitivity is shifted 52 times toward larger wavelength compared to that of LISA. The mission orbits of the 3 spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The 3 spacecraft range interferometrically with one another with arm length about 260 million kilometers. In order to attain the requisite sensitivity for ASTROD-GW, laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. For suppressing laser frequency noise, we need to use time delay interferometry (TDI) to match the two different optical paths (times of travel). Since planets and other solar-system bodies perturb the orbits of ASTROD-GW spacecraft and affect the (TDI), we simulate the time delay numerically using CGC 2.7 ephemeris framework. To conform to the ASTROD-GW planning, we work out a set of 20-year optimized mission orbits of ASTROD-GW spacecraft starting at June 21, 2028, and calculate the residual optical path differences in the first and second generation TDI for one-detector case. In our optimized mission orbits for 20 years, changes of arm length are less than 0.0003 AU; the relative Doppler velocities are less than 3m/s. All the second generation TDI for one-detector case satisfies the ASTROD-GW requirement., Comment: 17 pages, 7 figures, 1 table
- Published
- 2013
29. Influence of wet chemical cleaning on quantum efficiency of GaN photocathode
- Author
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Pin Gao, Benkang Chang, Hong-Gang Wang, Xiaohui Wang, and Biao Li
- Subjects
chemistry.chemical_compound ,Materials science ,X-ray photoelectron spectroscopy ,chemistry ,Annealing (metallurgy) ,General Physics and Astronomy ,Hydrochloric acid ,Sulfuric acid ,Quantum efficiency ,Contamination ,Hydrogen peroxide ,Photocathode ,Nuclear chemistry - Abstract
GaN samples 1–3 are cleaned by a 2:2:1 solution of sulfuric acid (98%) to hydrogen peroxide (30%) to de-ionized water; hydrochloric acid (37%); or a 4:1 solution of sulfuric acid (98%) to hydrogen peroxide (30%). The samples are activated by Cs/O after the same annealing process. X-ray photoelectron spectroscopy after the different ways of wet chemical cleaning shows: sample 1 has the largest proportion of Ga, N, and O among the three samples, while its C content is the lowest. After activation the quantum efficiency curves show sample 1 has the best photocathode performance. We think the wet chemical cleaning method is a process which will mainly remove C contamination.
- Published
- 2013
30. Impurity-induced local modes in one-dimensional dusty plasma chains
- Author
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Yong-Chao Ren, Xin-Shang Wang, and Xiao-Gang Wang
- Subjects
Physics ,Dusty plasma ,Condensed matter physics ,Physics::Plasma Physics ,Impurity ,High Energy Physics::Lattice ,Dispersion relation ,Lattice (order) ,Excited state ,General Physics and Astronomy ,Excitation - Abstract
The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied. It is found that local modes can be excited besides lattice waves, due to the existence of an impurity particle. The dispersion relations of the modes are derived accordingly. Properties of the lattice and local modes are also analyzed and discussed, particularly for their symmetric features and conditions of the mode excitation.
- Published
- 2012
31. Near-field properties of a shell nanocylinder pair with gain materials
- Author
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Shifa Wu, Qiao Wang, and Xiao-Gang Wang
- Subjects
Core (optical fiber) ,Materials science ,Field (physics) ,law ,Gap width ,Shell (structure) ,General Physics and Astronomy ,Near and far field ,Atomic physics ,Absorption (electromagnetic radiation) ,Resonance (particle physics) ,Cylinder (engine) ,law.invention - Abstract
We study the near-field response of a shell nanocylinder pair, with its core filled by gain materials, using a two-dimensional finite-difference time-domain method. It is shown that the gain materials in the core of the cylinder can compensate for the intrinsic absorption of the metal shell, leading to local-field enhancement in the gap of the active pair. A linear dependence is found between the field enhancement and the gain coefficient at resonance. The detailed physics is studied by calculating the electrical-field distribution of the shell pair filled with different gain materials. The influence of the gap width and the shell thickness on the interaction of two adjacent active shell cylinders is also investigated.
- Published
- 2012
32. Monolithic integration of an AlGaN/GaN metal—insulator field-effect transistor with an ultra-low voltage-drop diode for self-protection
- Author
-
Zhaoji Li, Zhi-Gang Wang, Bo Zhang, Jing Zhang, and Wan-Jun Chen
- Subjects
Materials science ,business.industry ,Drop (liquid) ,Transistor ,General Physics and Astronomy ,law.invention ,law ,Optoelectronics ,Field-effect transistor ,business ,Low voltage ,MISFET ,Voltage drop ,Diode ,Voltage - Abstract
In this paper, we present a monolithic integration of a self-protected AlGaN/GaN metal—insulator field-effect transistor (MISFET). An integrated field-controlled diode on the drain side of the AlGaN/GaN MISFET features a self-protected function for a reverse bias. This diode takes advantage of the recessed-barrier enhancement-mode technique to realize an ultra-low voltage drop and a low turn-ON voltage. In the smart monolithic integration, this integrated diode can block a reverse bias (> 70 V/μm) and suppress the leakage current (< 5 × 10−11 A/mm). Compared with conventional monolithic integration, the numerical results show that the MISFET integrated with a field-controlled diode leads to a good performance for smart power integration. And the power loss is lower than 50% in conduction without forward current degeneration.
- Published
- 2012
33. Highly efficient four-wave mixing induced by quantum constructive interference in rubidium vapour
- Author
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Jin-Yue Gao, Gang Wang, Yi Qu, Cui-Li Cui, and Yan Xue
- Subjects
Work (thermodynamics) ,Materials science ,business.industry ,Energy conversion efficiency ,General Physics and Astronomy ,chemistry.chemical_element ,Molecular physics ,Signal ,Rubidium ,Four-wave mixing ,Optics ,chemistry ,business ,Quantum ,Intensity (heat transfer) ,Mixing (physics) - Abstract
We demonstrate efficient four-wave mixing with an intensity conversion efficiency of nearly 100% in theory without considering the Doppler-broadening effect in a four-level double-Λ system of hot 87Rb gas. The corresponding experimental value of about 73% was reported in our earlier work under the same conditions. This dramatic efficiency is critically dependent on the constructive interference between two four-wave mixing processes relevant to the internally generated four-wave mixing signal.
- Published
- 2012
34. Scattering of light waves by electron electrostatic waves in laser produced plasmas
- Author
-
Zhan-Jun, Liu, primary, Jiang, Xiang, additional, Chun-Yang, Zheng, additional, Shao-Ping, Zhu, additional, Li-Hua, Cao, additional, Xian-Tu, He, additional, and Yu-Gang, Wang, additional
- Published
- 2010
- Full Text
- View/download PDF
35. A novel partial silicon on insulator high voltage LDMOS with low-k dielectric buried layer
- Author
-
Xiao-Rong, Luo, primary, Yuan-Gang, Wang, additional, Hao, Deng, additional, and Udrea, Florin, additional
- Published
- 2010
- Full Text
- View/download PDF
36. Damage of low-energy ion irradiation on copper nanowire: molecular dynamics simulation
- Author
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Xue-Qing, Zou, primary, Jian-Ming, Xue, additional, and Yu-Gang, Wang, additional
- Published
- 2010
- Full Text
- View/download PDF
37. Thermal relaxation of exchange bias field in an exchange coupled CoFe/IrMn bilayer
- Author
-
Xian-Jin, Qi, primary, Yin-Gang, Wang, additional, Guang-Hong, Zhou, additional, Zi-Quan, Li, additional, and Min, Guo, additional
- Published
- 2010
- Full Text
- View/download PDF
38. Influence of Ga + ion irradiation on the magnetisation reversal process and magnetoresistance in CoFe/Cu/CoFe/IrMn spin valves
- Author
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Xian-Jin, Qi, primary, Yin-Gang, Wang, additional, Xue-Fei, Miao, additional, Zi-Quan, Li, additional, and Yi-Zhong, Huang, additional
- Published
- 2010
- Full Text
- View/download PDF
39. Orbital magnetization in semiconductors
- Author
-
Cheng, Fang, primary, Zhi-Gang, Wang, additional, Shu-Shen, Li, additional, and Ping, Zhang, additional
- Published
- 2009
- Full Text
- View/download PDF
40. Dispersion relations of lattice waves in three-dimensional strongly coupled complex plasma crystals
- Author
-
Xue-Feng, Yang, primary, Xiao-Gang, Wang, additional, and Yue, Liu, additional
- Published
- 2009
- Full Text
- View/download PDF
41. Magnetization of two-dimensional heavy holes with boundaries in a perpendicular magnetic field
- Author
-
Cheng, Fang, primary, Zhi-Gang, Wang, additional, Shu-Shen, Li, additional, and Ping, Zhang, additional
- Published
- 2009
- Full Text
- View/download PDF
42. Analysis of the decay B 0 → χ c 1 π 0 with light-cone QCD sum rules
- Author
-
Zhi-Gang, Wang, primary
- Published
- 2009
- Full Text
- View/download PDF
43. Thermally activated magnetization reversal in magnetic tunnel junctions
- Author
-
Guang-Hong, Zhou, primary, Yin-Gang, Wang, additional, Xian-Jin, Qi, additional, Zi-Quan, Li, additional, and Jian-Kang, Chen, additional
- Published
- 2009
- Full Text
- View/download PDF
44. Optimizing bowtie structure parameters for specific incident light
- Author
-
Xu-Feng Li, Xiao-Gang Wang, Shifa Wu, and Qiao Wang
- Subjects
Physics ,Wavelength ,Optics ,business.industry ,Aperture ,Excited state ,Finite-difference time-domain method ,General Physics and Astronomy ,Resonance ,business ,Ray ,Local field ,Intensity (heat transfer) - Abstract
We investigate optical properties of a bowtie-shaped aperture using the finite difference time domain method to optimize its geometric parameters for specific incident lights. The influence of the parameters on local field enhancement and resonant wavelength in the visible frequency range is numerically analysed. It is found that the major resonance of the spectrum is exponentially depended on the bowtie angle but independent of the whole aperture size. The simulation also demonstrates that increasing the aperture size raises the local field intensity on the exit plane due to an enlarged interaction area between the light and the metal medium. And the near-field spot size is closely related to the gap. Based on these results, the design rules of the bowtie structure can be optimized for specific wavelengths excited.
- Published
- 2010
45. Synthesis and characterization of axially periodic Zn 2 SnO 4 dendritic nanostructures
- Author
-
Jun, Shen, primary, Bing-Hui, Ge, additional, Wei-Guo, Chu, additional, Shu-Dong, Luo, additional, Zeng-Xing, Zhang, additional, Dong-Fang, Liu, additional, Li-Feng, Liu, additional, Wen-Jun, Ma, additional, Yan, Ren, additional, Yan-Juan, Xiang, additional, Chao-Ying, Wang, additional, Gang, Wang, additional, and Wei-Ya, Zhou, additional
- Published
- 2008
- Full Text
- View/download PDF
46. Comparison of the mechanism of gap formation for tri- and bi-component phononic crystal
- Author
-
Hong-Gang, Zhao, primary, Ji-Hong, Wen, additional, Yao-Zong, Liu, additional, Dian-Long, Yu, additional, Gang, Wang, additional, and Xi-Sen, Wen, additional
- Published
- 2008
- Full Text
- View/download PDF
47. Dynamic surface wettability of three-dimensional graphene foam.
- Author
-
Wen-Bin, Huang, Guang-Long, Wang, Feng-Qi, Gao, Zhong-Tao, Qiao, Gang, Wang, Min-Jiang, Chen, Li, Tao, Ya, Deng, and Lian-Feng, Sun
- Subjects
VAPORIZATION in water purification ,SCANNING electron microscopes ,RAMAN spectroscopy ,ELECTRIC properties of graphene ,WETTING ,WATER seepage - Abstract
In this work, three-dimensional graphene foams (GFs) are synthesized and characterized by scanning electron microscope (SEM) and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel (Ni) foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are ∼ 58%, ∼ 32%, ∼ 8%, and ∼ 2%, respectively. The contact angle (CA) (∼ 12°) of water droplet (3 μL) on GF is found to be larger than that on Ni foam (∼ 107°), indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
48. Vertical structure of predictability and information transport over the Northern Hemisphere.
- Author
-
Ai-Xia, Feng, Qi-Gang, Wang, Zhi-Qiang, Gong, and Guo-Lin, Feng
- Subjects
- *
NONLINEAR systems , *PREDICTION theory , *INFORMATION theory , *TROPOSPHERE , *TELECONNECTIONS (Climatology) - Abstract
Based on nonlinear prediction and information theory, vertical heterogeneity of predictability and information loss rate in geopotential height field are obtained over the Northern Hemisphere. On a seasonal-to-interannual time scale, the predictability is low in the lower troposphere and high in the mid-upper troposphere. However, within mid-upper troposphere over the subtropics ocean area, there is a relatively poor predictability. These conclusions also fit the seasonal time scale. Moving to the interannual time scale, the predictability becomes high in the lower troposphere and low in the mid-upper troposphere, contrary to the former case. On the whole the interannual trend is more predictable than the seasonal trend. The average information loss rate is low over the mid-east Pacific, west of North America, Atlantic and Eurasia, and the atmosphere over other places has a relatively high information loss rate on all-time scales. Two channels are found steadily over the Pacific Ocean and Atlantic Ocean in subtropics. There are also unstable channels. The four-season influence on predictability and information communication are studied. The predictability is low, no matter which season data are removed and each season plays an important role in the existence of the channels, except for the winter. The predictability and teleconnections are paramount issues in atmospheric science, and the teleconnections may be established by communication channels. So, this work is interesting since it reveals the vertical structure of predictability distribution, channel locations, and the contributions of different time scales to them and their variations under different seasons. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
49. Different influences of Schottky metal on the strain and relative permittivity of barrier layer between AlN/GaN and AlGaN/GaN heterostructure Schottky diodes.
- Author
-
Yuan-Jie, Lü, Zhi-Hong, Feng, Guo-Dong, Gu, Shao-Bo, Dun, Jia-Yun, Yin, Yuan-Gang, Wang, Peng, Xu, Ting-Ting, Han, Xu-Bo, Song, Shu-Jun, Cai, Chong-Biao, Luan, and Zhao-Jun, Lin
- Subjects
SCHOTTKY barrier diodes ,STRAINS & stresses (Mechanics) ,PERMITTIVITY ,ALUMINUM nitride ,GALLIUM nitride ,HETEROSTRUCTURES - Abstract
Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated. Based on the measured current—voltage and capacitance-voltage curves, the polarization sheet charge density and relative permittivity are analyzed and calculated by self-consistently solving Schrödinger's and Poisson's equations. It is found that the values of relative permittivity and polarization sheet charge density of AlN/GaN diode are both much smaller than the ones of AlGaN/GaN diode, and also much lower than the theoretical values. Moreover, by fitting the measured forward I—V curves, the extracted dislocations existing in the barrier layer of the AlN/GaN diode are found to be much more than those of the AlGaN/GaN diode. As a result, the conclusion can be made that compared with AlGaN/GaN diode the Schottky metal has an enhanced influence on the strain of the extremely thinner AlN barrier layer, which is attributed to the more dislocations. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
50. Online multiple instance regression.
- Author
-
Zhi-Gang, Wang, Zeng-Shun, Zhao, and Chang-Shui, Zhang
- Subjects
- *
REGRESSION analysis , *BIG data , *RESEARCH , *K-nearest neighbor classification , *MULTIVARIATE analysis - Abstract
The multiple instance regression problem has become a hot research topic recently. There are several approaches to the multiple instance regression problem, such as Salience, Citation KNN, and MI-ClusterRegress. All of these solutions work in batch mode during the training step. However, in practice, examples usually arrive in sequence. Therefore, the training step cannot be accomplished once. In this paper, an online multiple instance regression method “OnlineMIR" is proposed. OnlineMIR can not only predict the label of a new bag, but also update the current regression model with the latest arrived bag. The experimental results show that OnlineMIR achieves good performances on both synthetic and real data sets. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
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