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Dynamical Symmetries of Two-Dimensional Dirac Equation with Screened Coulomb and Isotropic Harmonic Oscillator Potentials

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Communications in Theoretical physics 2014年第11期61卷 663-666页

作者：王青侯玉龙隆正文荆坚 College of Physics Science and Technology Xinjiang University Department of Physics and Electronic School of Science Beijing University of Chemical Technology Laboratory for Photoelectric Technology and Application Department of Physics Guizhou University

In this paper, we study symmetrical properties of two-dimensional(2D) screened Dirac Hydrogen atom and isotropic harmonic oscillator with scalar and vector potentials of equal magnitude(SVPEM). We find that it is possible for both cases to preserve so(3) and su(2) dynamical symmetries provided certain conditions are satisfied. Interestingly,the conditions for preserving these dynamical symmetries are exactly the same as non-relativistic screened Hydrogen atom and screened isotropic oscillator preserving their dynamical symmetries. Some intuitive explanations are proposed.

关键词： dynamical symmetry Dirac oscillator isotropic Hydrogen oscillator

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Intermittent operating life results for different control strategies

Intermittent operating life results for different control st...

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International Conference on electronic Packaging technology

作者： Yuan Chen Bo Hou Science and Technology on Reliability Physics and Application of Electronic Component Laboratory The 5~(th) Electronic Institute of MII Guangzhou China

ISBN: (纸本)9781467380003

Intermittent operating life test is an important method to characterize the lifetime and package reliability of power semiconductor devices. The control strategy is a very important feature of the intermittent operating life test. Intermittent operating life tests with identical start condition but different control strategies (temperature control strategy and time control strategy) have been performed, which have been conducted on specially assembled test equipment with ultimate control of all test parameters. The test results under these two different control strategies are analyzed and discussed. Failure analysis is also used, to understand the failure mechanisms induced by intermittent operating life tests. The changes of thermal resistance with intermittent life cycle number are compared under two control strategies. The results show, that time control strategy is more severe than temperature control strategy. The lifetime of power devices is longer under temperature control strategy. And the thermal resistance increases relatively larger by time control strategy

关键词： Intermittent Operating Life Temperature Control Strategy Time Control Strategy Power Semiconductor Device

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Interface states in Al_2O_3/AlGaN/GaN metal-oxide-semiconductor structure by frequency dependent conductance technique

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Chinese physics B 2014年第5期23卷 505-509页

作者：廖雪阳张凯曾畅郑雪峰恩云飞来萍郝跃 Science and Technology on Reliability Physics and Application of Electronic Component Laboratory the 5th Electronics Research Institute of the Ministry of Industry and Information Technology Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

Frequency dependent conductance measurements are implemented to investigate the interface states in Al2O3/A1GaN/GaN metal-oxide-semiconductor （MOS） structures. Two types of device structures, namely, the recessed gate structure （RGS） and the normal gate structure （NGS）, are studied in the experiment. Interface trap parameters includ-ing trap density Dit, trap time constant ιit, and trap state energy ET in both devices have been determined. Furthermore, the obtained results demonstrate that the gate recess process can induce extra traps with shallower energy levels at the Al2O3/AlGaN interface due to the damage on the surface of the AlGaN barrier layer resulting from reactive ion etching （RIE）.

关键词： Al2O3/AlGaN/GaN interface trap states conductance capacitance

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Harmonic vibration analysis and S-N curve estimate of PBGA mixed solder joints 15

Harmonic vibration analysis and S-N curve estimate of PBGA m...

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2014 15th International Conference on electronic Packaging technology, ICEPT 2014

作者： Lu, Tao Zhou, Bin Pan, Kailin En, Yunfei Gong, Yubin School of Mechanical and Electrical Engineering Guilin University of Electronic Technology Guilin China Science and Technology on Reliability Physics and Application of Electronic Component Laboratory Guangzhou China

ISBN: (纸本)9781479947072

With the development of lead-free in electronic products, mixed soldering of lead-free component with lead solder is inevitable in high reliability electronic assembly. For the mixed assemblies, the primary task is to ensure the reliability of mixed solder joints. This study is aimed at finding out the harmonic vibration fatigue properties of plastic ball grid array (PBGA) mixed solder joints under 1st natural frequency and getting the relation curve between equivalent stress and number of fatigue cycles of the mixed solder joints. A specified PBGA assembly was designed with a piece of daisy-chained printed circuit board (PCB). Modal test and harmonic vibration test were implemented. The PCB strain was measured by strain gages, and the time to failure of solder joints was monitored by an event detector. After comparing natural frequencies, modal shapes and PCB strain with the simulation corresponding results, finite element model (FEM) was validated. Then, the volume averaged equivalent stress of mixed solder joints was discovered with modified model. Finally, S-N curve of mixed solder joints was fitted with Basquin power law relation. In the hopeful future, combining the fitted S-N curve with other methodologies, the vibration fatigue life of mixed solder joints could be estimated. © 2014 IEEE.

关键词： Natural frequencies

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A high gain wide dynamic range transimpedance amplifier for optical receivers

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Journal of Semiconductors 2014年第1期35卷 78-83页

作者：刘帘曦邹姣恩云飞刘术彬牛越朱樟明杨银堂 School of Microelectronics Xidian University Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices National Key Laboratory of Science and Technology on Reliability Physics and Application Technology of Electrical Component

As the front-end preamplifiers in optical receivers, transimpedance amplifiers （TIAs） are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range （DR） to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.

关键词： transimpedance amplifier high gain inductive-series peaking wide dynamic range

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Characterization of a magnetic field probe for electromagnetic interference current measurement

Characterization of a magnetic field probe for electromagnet...

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作者： Li, Fan Fang, Wen Xiao Lei, Liang Liu, Yuan Shi, Chun Lei Science and Technology on Reliability Physics and Application of Electronic Component Laboratory CEPREI GuangZhou China School of Physics and Optoelectronic Engineering GuangDong University of Technology GuangZhou China

ISBN: (纸本)9783038351382

This paper investigates a miniature rectangular triplate-printed antenna, which acts as a magnetic field probe to estimate amplitude of the RF Electromagnetic Interference current by noncontact measurement. To characterize the probe, a current transfer factor defined as the ratio of the probed voltage over the current is investigated by measuring the frequency-dependent S-parameter. Moving and rotating the probe will change the current transfer factor, and then significantly affect the estimation of the RF current under detection. To specify the application of the probe, the spatial dependences of the current transfer factor are systematically studied, and in agreement with the calculation of the magnetic field generated by the RF current. © (2014) Trans Tech Publications, Switzerland.

关键词： Signal interference

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Dynamic fracture characteristics of cylindrical steel shell under internal blast loading

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International Journal of Materials and Structural Integrity 2015年第4期8卷 291-302页

作者： Hu, Yongle Liu, Qicheng Bai, Shuxin Zhang, Hong Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science and Technology ChangshaHunan Province410004 China College of Physics and Electronic Science Changsha University of Science and Technology Changsha410004 China College of Aerospace and Material Engineering National University of Defense Technology Changsha300072 China

Dynamic fracture characteristics are the foundation for conducting safety assessment and failure analysis of explosion containment vessels (ECVs) subjected to internal blast loading. The experiment was conducted to investigate dynamic fracture characteristics of cylindrical steel shells subjected to internal blast loading at the centre. The elastic-plastic response of cylindrical steel shells was simulated numerically by using nonlinear dynamic finite element analysis code LS-DYNA. The fracture mode and mechanism of a cylindrical shell were specially studied by means of the analysis of deformation, macrographs and meso-graphs of fracture surface and elastic-plastic response. The results show that the axial direction fracture surface of the cylindrical steel shell exhibits a mixed ductile fracture mode with shearing dimple by micro-voids coalescence. Dynamical ductility deformations appear and the shear bands form when the cylindrical steel shell expands under internal blast loading. The fracture mechanism is that the shear bands destroyed the initiation and growth of the micro-voids and micro-cracks along the shear bands due to its softening effect under tensile circumferential stress. The shear bands and the tensile circumferential stress dominate the final fracture mode. The fracture mode is the ductile fracture. Copyright © 2014 Inderscience Enterprises Ltd.

关键词： Shear bands

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Fatigue life prediction and verification for HIC hermetical sealing under random vibration loading 3

Fatigue life prediction and verification for HIC hermetical ...

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3rd Asian Pacific Conference on Mechanical Components and Control Engineering (ICMCCE)

作者： He, Xiaoqi Wang, Junde Zhu, Junhua Li, Xunping Liu, Junfu Science and Technology on Reliability Physics and Application of Electronic Component Laboratory China South China University of Technology School of Materials Science and Engineering China East China Research Institute of Microelectronic China

ISBN: (纸本)9783038353126

This work aims to predict fatigue life of hybrid integrated circuit (HIC) hermetical metal sealing structure mounted on PCB under random vibration loading. The prediction method consists of following steps. Firstly, finite-element model was developed to obtain model parameters (including natural frequencies and mode shapes) and power spectral density (PSD) of the critical part of sealing structure by ANSYS workbench. Secondly, modal test and random vibration test were conducted to verify the results of simulation. Thirdly, the Von Mises stress PSD was transformed into time-history data through inverse Fourier transform with Matlab program after calculating from the FEA results. The rainflow-counting algorithm was employed to evaluate cumulative damages of the critical part. The material's S-N curve, Palmgren-Miner's damage accumulation rule and rainflow-counting algorithm were used to predict fatigue life. A specially designed fixture and board with heat sink were used in the experiment to verify the first five mode shapes and response spectrum of the six critical points with hammer excitation. The calculation result of in this study is 70.3 hours which could be a reference for structural design of hybrid integrated circuit hermetical metal sealing under vibration conditions.

关键词： Hybrid integrated circuit Hermetical sealing Mode shape Random vibration Fatigue life prediction

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Chirality Quantum Phase Transition in Noncommutative Dirac Oscillator

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Communications in Theoretical physics 2014年第12期61卷 833-838页

作者：王少华侯玉龙王青隆政文荆坚 Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Department of Physics and Electronic School of Science Beijing University of Chemical Technology College of Physics Science and Technology Xinjiang University Laboratory for Photoelectric Technology and Application Department of Physics Guizhou University

The charged Dirac oscillator on a noncommutative plane coupling to a uniform perpendicular magnetic field is studied in this paper. We map the noncommutative plane to a commutative one by means of Bopp shift and study this problem on the commutative plane. We find that this model can be mapped onto a quantum optics model which contains Anti–Jaynes–Cummings(AJC) or Jaynes–Cummings(JC) interactions when a dimensionless parameterζ(which is the function of the intensity of the magnetic field) takes values in different regimes. Furthermore, this model behaves as experiencing a chirality quantum phase transition when the dimensionless parameter ζ approaches the critical point. Several evidences of the chirality quantum phase transition are presented. We also study the non-relativistic limit of this model and find that a similar chirality quantum phase transition takes place in its non-relativistic limit.

关键词： Anti-Jaynes–Cummings interaction Jaynes–Cummings interaction Chirality quantum phase transition

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Investigation of high-temperature-reverse-bias (HTRB) degradation on AlGaN/GaN HEMTs

Investigation of high-temperature-reverse-bias (HTRB) degrad...

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2014 IEEE International Conference on Electron Devices and Solid-State Circuits, EDSSC 2014

作者： Liao, Xueyang Wang, Yuansheng Chang, Zeng Li, Ruguan Chen, Yiqiang Ping, Lai Yun, Huang En, Yunhui Science and Technology on Reliability Physics and Application of Electronic Component Laboratory 5th Electronics Research Institute Ministry of Industry and Information Technology GuangZhou China

ISBN: (纸本)9781479923342

AlGaN/GaN HEMTs are performed to the HTRB stress experiments to investigate the degradation phenomena. Several degradation characteristics of DC parameters such as the reduction of saturated drain current, the increase of gate leakage current and on-resistance, and the shift of threshold voltage are identified. The degradation mechanism is ascribed to the trapping of electrons in the region under the gate and the access region of gate to drain. The degradation speed of the bottom fingers is faster than the upside fingers, which meant the improvement of thermal design is important for the reliability enhancement of AlGaN/GaN HEMTs. © 2014 IEEE.

关键词： Threshold voltage

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