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Structural relaxation and avalanche dynamics of particle piles under vertical vibration

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Particuology 2022年第9期20卷 65-74页

作者： Lizhuo Zhu Haifeng Lu Xiaolei Guo Haifeng Liu Shanghai Engineering Research Center of Coal Gasifiication East China University of Science and TechnologyShanghai 200237China

Granular matter can exhibit solid or liquid behavior,which contains complex physical mechanisms.In this work,we experimentally investigated the structural relaxation and avalanche dynamics of particle piles under vertical vibration.The influence of vibration parameters on the avalanche process was studied.The morphological features of avalanches were recorded and classified using high-speed camera.The effects of vibration parameters and particle properties on the relaxation mode are obtained.It is found that the evolution of particle pile height with time can be described by an exponential decay function.The relaxation rate and avalanche characteristics of four types of particles with different sizes are discussed.At the same acceleration level,for two larger particles,a smaller amplitude(A=0.025 mm)leads to a faster relaxation rate,while for two smaller particles,a large amplitude(A=0.500 mm)leads to a faster relaxation rate.The analogy powder surface tension is introduced to address the cohesion and flowability evolution of particles under vibration.

关键词： Particle pile Vertical vibration avalanche Flowability

Ultra-low dark count InGaAs/InP single photon avalanche diode

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Optoelectronics Letters 2022年第11期18卷 647-650页

作者： LI Bin NIU Yuxiu FENG Yinde CHEN Xiaomei Accelink Technologies Co. Ltd.Wuhan430000China

A low noise InGaAs/InP single photon avalanche diode(SPAD) is demonstrated. The device is based on planar type separate absorption, grading, charge and multiplication structure. Relying on reasonably designed device structure and low-damage Zn diffusion technology, excellent low-noise performance is achieved. Due to its importance, the physical mechanism of dark count is analyzed through performance characterization at different temperatures. The device can achieve 20% single photon detection efficiency and 320 Hz dark count rate(DCR) with a low after pulsing probability of 0.57% at 233 K.

关键词： InGaAs/InP diode avalanche

Terahertz wave avalanche breakdown transistor for high-performance switching

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Photonics Research 2021年第3期9卷 370-378页

作者： Weijun WANG Liang-Hui Du Jiang Li Pei-Ren Tang Changlin Sun Songlin Chen Jun Wang Zhao-Hui Zhai Zhipeng Gao Ze-Ren Li Jianquan Yao Furi Ling Li-Guo Zhu Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Microsystem&Terahertz Research Center China Academy of Engineering PhysicsChengdu 610200China School of Optoelectronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China College of Precision Instrument and Optoelectronics Engineering Tianjin UniversityTianjin 300072China

There is still a lack of high-performance terahertz(THz) modulators with wide operation bandwidth and large modulation depth due to the underlying physics limitation behind existing approaches. Meanwhile, for many applications, simple compact THz modulators working straightforward in the transmission mode are also highly desired. Here, we demonstrate a THz modulator with a maximal transmission-amplitude modulation depth of 99.9%(switching ratio of 1000) based on a commonly used silica-on-silicon structure. Different from those reported graphene or metamaterials enhanced proposals, the device we proposed works within a reversible avalanche breakdown region of silicon that has not been studied yet and has the potential to modulate/switch THz waves efficiently. Further, we proved that the modulation depth exceeds 97% in the frequency range from 0.2 to 1 THz in the experiment. The simplicity and generality of this new type of near-perfect THz modulator will undoubtedly attract lots of attention of researchers in the near future due to its potential to be engineered into integrated devices.

关键词： breakdown modulator avalanche

Interface Electric Field Confinement Effect of High-Sensitivity Lateral Ge/Si avalanche Photodiodes

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Tsinghua Science and Technology 2019年第1期24卷 1-8页

作者： Wenzhou Wu Zhi Liu Jun Zheng Yuhua Zuo Buwen Cheng the State Key Laboratory on Integrated Optoelectronics Institute of Semiconductor Chinese Academy of Sciences the College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences

A novel lateral Ge/Si avalanche photodiode without a charge region is investigated herein using device physical simulation. High field is provided by the band-gap barrier and build-in field at the Ge/Si interface in the vertical direction. Modulating the Si mesa thickness(0-0.4 μm) and impurity concentration of the intrinsic Si substrate(1×10^(16)-4×10^(16)cm^(-3)) strengthens the electric field confinement in the substrate region and provides a high avalanche multiplication in the Si region. When the Si mesa thickness is 0.3 μm, and the impurity concentration of the Si substrate is 2×10^(16) cm^(-3), the Lateral avalanche PhotoDiode(LAPD) exhibits a peak gain of 246 under 1.55 μm incident light power of -22.2 dBm, which increases with decreasing light intensity.

关键词： avalanche photodiodes lateral structure electric field confinement high gain

Dark count in single-photon avalanche diodes:A novel statistical behavioral model

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Chinese Physics B 2020年第4期29卷 523-529页

作者：喻文娟张钰许明珠逯鑫淼 School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China

Dark count is one of the inherent noise types in single-photon diodes,which may restrict the performances of detectors based on these diodes.To formulate better designs for peripheral circuits of such diodes,an accurate statistical behavioral model of dark current must be established.Research has shown that there are four main mechanisms that contribute to the dark count in single-photon avalanche diodes.However,in the existing dark count models only three models have been considered,thus leading to inaccuracies in these models.To resolve these shortcomings,the dark current caused by carrier diffusion in the neutral region is deduced by multiplying the carrier detection probability with the carrier particle current at the boundary of the depletion layer.Thus,a comprehensive dark current model is constructed by adding the dark current caused by carrier diffusion to the dark current caused by the other three mechanisms.To the best of our knowledge,this is the first dark count simulation model into which incorporated simultaneously are the thermal generation,trap-assisted tunneling,band-to-band tunneling mechanisms,and carrier diffusion in neutral regions to evaluate dark count behavior.The comparison between the measured data and the simulation results from the models shows that the proposed model is more accurate than other existing models,and the maximum of accuracy increases up to 31.48%when excess bias voltage equals 3.5 V and temperature is 50℃.

关键词： single-photon avalanche diode dark count statistical behavioral modeling carrier diffusion

Three-terminal germanium-on-silicon avalanche photodiode with extended p-charge layer for dark current reduction

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Photonics Research 2022年第8期10卷 1956-1963页

作者： XIAOBIN LIU XUETONG LI YUXUAN LI YINGZHI LI ZIHAO ZHI MIN TAO BAISONG CHEN LANXUAN ZHANG PENGFEI GUO GUOQIANG LO XUEYAN LI FENGLI GAO BONAN KANG JUNFENG SONG State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China Advance Micro Foundry Pte Ltd Singapore 117685Singapore Peng Cheng Laboratory Shenzhen 518000China

Germanium-on-silicon(Ge-on-Si) avalanche photodiodes(APDs) are widely used in near-infrared detection, laser ranging, free space communication, quantum communication, and other fields. However, the existence of lattice defects at the Ge/Si interface causes a high dark current in the Ge-on-Si APD, degrading the device sensitivity and also increasing energy consumption in integrated circuits. In this work, we propose a novel surface illuminated Ge-on-Si APD architecture with three terminals. Besides two electrodes on Si substrates, a third electrode is designed for Ge to regulate the control current and bandwidth, achieving multiple outputs of a single device and reducing the dark current of the device. When the voltage on Ge is -27.5 V, the proposed device achieves a dark current of 100 n A, responsivity of 9.97 A/W at -40 d Bm input laser power at 1550 nm, and optimal bandwidth of 142 MHz. The low dark current and improved responsivity can meet the requirements of autonomous driving and other applications demanding weak light detection.

关键词： avalanche charge driving

Discrete Element Modeling of Tangjiagou Two-Branch Rock avalanche Triggered by the 2013 Lushan MW6.6 Earthquake,China

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Earthquake Research in China 2020年第1期34卷 81-95页

作者： CAO Yanbo XU Chong NAN Yalin School of Geological Engineering and Surveying Chang'an UniversityKey Laboratory of Western China Mineral Resources and Geological EngineeringXi'an 710054China Institute of Crustal Dynamics China Earthquake AdministrationBeijing 100085China China Electronic Research Institute of Engineering Investigations and Design Xi'an 710055China

Two branches of Tangjiagou rock avalanche were triggered by Lushan earthquake in Sichuan Province,China on April 20th,2013.The rock avalanche has transported about 1500000 m3 of sandstone from the source area.Based on discrete element modeling,this study simulates the deformation,failure and movement process of the rock avalanche.Under seismic loading,the mechanism and process of deformation,failure,and runout of the two branches are similar.In detail,the stress concentration occur firstly on the top of the mountain ridge,and accordingly,the tensile deformation appears.With the increase of seismic loading,the strain concentration zone extends in the forward and backward directions along the slipping surface,forming a locking segment.As a result,the slipping surface penetrates and the slide mass begin to slide down with high speed.Finally,the avalanche accumulates in the downstream and forms a small barrier lake.Modeling shows that a number of rocks on the surface exhibit patterns of horizontal throwing and vertical jumping under strong ground shaking.We suggest that the movement of the rock avalanche is a complicated process with multiple stages,including formation of the two branches,high-speed sliding,transformation into debris flows,further movement and collision,accumulation,and the final steady state.Topographic amplification effects are also revealed based on acceleration and velocity of special monitoring points.The horizontal and vertical runout distances of the surface materials are much greater than those of the internal materials.Besides,the sliding duration is also longer than that of the internal rock mass.

关键词： Tangjiagou two-branch rock avalanche Lushan earthquake Deformation and movement process Discrete element modeling

A GaN p-i-p-i-n Ultraviolet avalanche Photodiode

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Chinese Physics Letters 2012年第9期29卷 193-195页

作者：郑纪元汪莱郝智彪罗毅王兰喜陈学康 Tsinghua National Laboratory for Information Science and Technology State Key Laboratory on Integrated OptoelectronicsDepartment of Electronic EngineeringTsinghua UniversityBeijing 100084 Science and Technology on Surface Engineering Laboratory Lanzhou Institute of PhysicsLanzhou 730000

A separated absorption and multiplication GaN p–i–p–i–n avalanche photo-diode(APD)with a 25μm diameter mesa is proposed and demonstrated.Compared to the conventional p–i–n APD,the p–i–p–i–n structure reduces the probability of premature micro-plasma breakdown,raises the gain from 30 to 400 and reduces the work voltage from 93 to 48 V.The temperature test is set on p–i–p–i–n APDs,and the positive coefficient of 30 mV/K shows that avalanche breakdown happens in the devices.The peak responsivity of p–i–p–i–n APDs is 0.11 A/W under a wavelength of 358 nm.

关键词： breakdown GaN avalanche

Mechanisms of enhanced sub-bandgap absorption in high-speed all-silicon avalanche photodiodes

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Photonics Research 2023年第2期11卷 337-346页

作者： YUAN YUAN WAYNE V.SORIN DI LIANG STANLEY CHEUNG YIWEI PENG MUDIT JAIN ZHIHONG HUANG MARCO FIORENTINO RAYMOND G.BEAUSOLEIL Hewlett Packard Labs Hewlett Packard EnterpriseMilpitasCalifornia 95035USA

All-silicon (Si) photodiodes have drawn significant interest due to their single and simple material system and perfect compatibility with complementary metal-oxide semiconductor photonics. With the help from a cavity enhancement effect, many of these photodiodes have shown considerably high responsivity at telecommunication wavelengths such as 1310 nm, yet the mechanisms for such high responsivity remain unexplained. In this work,an all-Si microring is studied systematically as a photodiode to unfold the various absorption mechanisms.At-6.4 V, the microring exhibits responsivity up to0.53 A∕W with avalanche gain, a 3 dB bandwidth of25.5 GHz, and open-eye diagrams up to 100 Gb/s. The measured results reveal the hybrid absorption mechanisms inside the device. A comprehensive model is reported to describe its working principle, which can guide future designs and make the all-Si microring photodiode a promising building block in Si photonics.

关键词： Gb/s avalanche absorption