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The effect of working gas pressure and deposition power on the properties of molybdenum films deposited by DC magnetron sputtering

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Science China(Technological Sciences) 2014年第5期57卷 947-952页

作者： CAO Hong ZHANG chuanJun chu junhao National Laboratory for Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai Center for Photovoltaics

Molybdenum films were deposited on Corning 7059 glass substrates by DC magnetron sputtering with different working gas pressures and sputtering *** structure and morphology,residual stress and adhesion,resistivity and optical reflectance of the as-deposited Mo films were *** results show that Mo films deposited with high working gas pressure and low sputtering power have a spherical surface morphology,small grain size,residual compressive stress and a good adhesion,high resistivity and low optical *** the working gas pressure decreased and the sputtering power increased,Mo films have elongated spindle-shape or diamond flake shape surface morphology,the grain size is increased,with residual stress changed from tensile to compressive,a poor adhesion,resistivity decreased and optical reflectance increased.

关键词： molybdenum thin films magnetron sputtering back contact solar cell

A novel technique for probing phase transitions in ferroelectric functional materials: Condensed matter spectroscopy

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Science China(Technological Sciences) 2016年第10期59卷 1537-1548页

作者： ZHANG JinZhong JIANG Kai HU ZhiGao chu junhao Department of Electronic Engineering East China Normal University

As relaxor ferroelectric functional materials, their crystal structures depend on temperature, component, electric filed, pressure, and so on, which are important for the applications of sensors, transducers, and actuators. For the case of PbTiO3-based ferroelectrics Pb（Zn2/3Nb2/3）O3-PbTiO3, Pb（Mg1/3Nb2/3）O3-PbTiO3, Pb（In1/2Nb1/2）O3-Pb（Mgu3Nb2/3）O3-PbTiO3 and some other crystals, they have been extensively investigated due to the excellent electromechanical and piezoelectric properties. Generally, ferroelectric crystal structure and corresponding phase diagram are detected by temperature-dependent high resolution X-ray diffraction, low frequency dielectric permittivity, and domain structures. In this review, we focus on the novel condensed matter spectroscopy （i.e., spectroscopic ellipsometry, transmittance, photoluminescence spectra as well as Raman spectra）, which is nondestructive, noncontact, and sensitive optical techniques for probing symmetries, phase transitions and phase diagrams of ferroelectric crystals. Besides, it can supply some other physical and chemical information for ferroelectric and semiconductor functional materials such as optical band gap, electronic transitions, dielectric functions, optical conductivity, absorption, pho- non modes, lattice dynamics as functions of temperature and PT composition.

关键词： ferroelectrics phase diagram Raman scattering ellipsometric spectroscopy transmittance photoluminescence

Review in situ transmission electron microscope with machine learning

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Journal of Semiconductors 2022年第8期43卷 10-23页

作者： Zhiheng Cheng Chaolun Wang Xing Wu junhao chu In Situ Devices Center Shanghai Key Laboratory of Multidimensional Information ProcessingEast China Normal UniversityShanghai 200241China

Advanced electronic materials are the fundamental building blocks of integrated circuits(ICs).The microscale properties of electronic materials(e.g.,crystal structures,defects,and chemical properties)can have a considerable impact on the performance of *** characterization and analysis of the material in real time with high-spatial resolution are *** situ transmission electron microscope(TEM)with atomic resolution and external field can be applied as a physical simulation platform to study the evolution of electronic material in working *** high-speed camera of the in situ TEM generates a high frame rate video,resulting in a large dataset that is beyond the data processing ability of researchers using the traditional *** overcome this challenge,many works on automated TEM analysis by using machine-learning algorithm have been *** this review,we introduce the technical evolution of TEM data acquisition,including analysis,and we summarize the application of machine learning to TEM data analysis in the aspects of morphology,defect,structure,and *** of the challenges of automated TEM analysis are given in the conclusion.

关键词： electron microscopy machine learning in situ image analysis semiconductor

First-principles study on the alkali chalcogenide secondary compounds in Cu(In,Ga)Se_2 and Cu_2ZnSn(S,Se)_4 thin film solar cells

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Journal of Energy Chemistry 2018年第4期27卷 1140-1150页

作者： Xian Zhang Dan Han Shiyou Chen chungang Duan junhao chu Key Laboratory of Polar Materials and Devices (MOE) East China Normal University Collaborative Innovation Center of Extreme Optics Shanxi University

The beneficial effect of the alkali metals such as Na and K on the Cu（***）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.

关键词： Cu(In,Ga)Se2 and Cu2ZnSn(S,Se)4 Thin film solar cells First-principles calculations Secondary phases Alkali dopants

Pulse-doubling perovskite nanowire lasers enabled by phonon-assisted multistep energy funneling

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Light(Science & Applications) 2024年第8期13卷 1645-1654页

作者： chunhu Zhao Jia Guo Jiahua Tao junhao chu Shaoqiang Chen Guichuan Xing Hunan Provincial Key Laboratory of Carbon Neutrality and Intelligent Energy School of Resource&EnvironmentHunan University of Technology and Business410205 ChangshaChina Engineering Research Center for Nanophotonics and Advanced Instrument Ministry of EducationSchool of Physics and Electronic ScienceEast China Normal University200241 ShanghaiChina Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials EngineeringUniversity of Macao999078 MacaoChina

Laser pulse multiplication from an optical gain medium has shown great potential in miniaturizing integrated optoelectronic *** multiple quantum wells(MQWs)structures have recently been recognized as an effective gain media capable of doubling laser pulses that do not rely on external optical *** the light amplifications enabled with pulse doubling are reported based on the perovskite MQWs thin films,the micronanolasers possessed a specific cavity for laser pulse multiplication and their corresponding intrinsic laser dynamics are still ***,a single-mode double-pulsed nanolaser from self-assembled perovskite MQWs nanowires is realized,exhibiting a pulse duration of 28 ps and pulse interval of 22 ps based on single femtosecond laser pulse *** is established that the continuous energy building up within a certain timescale is essential for the multiple population inversion in the gain medium,which arises from the slowing carrier localization process owning to the stronger exciton–phonon coupling in the smaller-n ***,the double-pulsed lasing is achieved from one fast energy funnel process from the adjacent small-n QWs to gain active region and another slow process from the spatially separated *** report may shed new light on the intrinsic energy relaxation mechanism and boost the further development of perovskite multiple-pulse lasers.

关键词： doubling energy phonon

Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection

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Light(Science & Applications) 2021年第4期10卷 600-609页

作者： Jinchao Tong Fei Suo Tianning Zhang Zhiming Huang junhao chu Dao Hua Zhang School of Electrical and Electronic Engineering Nanyang Technological UniversityNanyang Avenue639798 SingaporeSingapore State Key Laboratory of Infrared Physics Shanghai Institute of Technical

High-performance uncooled millimnetre and terahertz wave detectors are required as a building block for a wide range of *** state-of-the art technologies,however,are plagued by low sensitivity,narrow spectral bandwidth,and complicated ***,we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature *** making a nanogroove array in the grown InSb layer,strong millimetre and terahertz wave surface plasmon polaritons can be generated at the InSb-air interfaces,which results in significant improvement in detecting performance.A noise equivalent power(NEP)of 2.2× 10^(-14)WHz^(-1/2) or a detectivity(D)of 2.7× 10^(12)cmHz^(1/2) W^(-1) at 1.75 mm(0.171 THz)is achieved at room *** lowering the temperature to the thermoelectric cooling available 200 K,the corresponding NEP and D'of the nanogroove device can be improved to 3.8× 10^(-15)WHz^(-1/2) and 1.6× 10^(13) cm Hz^(-1/2) w^(-1),*** addition,such a single device can perform broad spectral band detection from 0.9 mm(0.330 THz)to 9.4 mm(0.032 THz).Fast responses of 3.5μs and 780 ns are achieved at room temperature and 200 K,*** high-performance millimnetre and terahertz wave photodetectors are useful for wide applications such as high capacity communications,walk-through security,biological diagnosis,spectroscopy,and remote *** addition,the integration of plasmonic semiconductor nanostructures paves a way for realizing high performance and multifunctional long-wavelength optoelectrical devices.

关键词： wave spectral terahertz

A new pathway towards all-electric spintronics:electric-field control of spin states through surface/interface effects

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Science China(Physics,Mechanics & Astronomy) 2013年第1期56卷 232-244页

作者： GONG ShiJing DING HangChen ZHU WanJiao DUAN chunGang ZHU ZiQiang chu junhao Key Laboratory of Polar Materials and Devices Ministry of EducationEast China Normal University National Laboratory for Infrared Physics Chinese Academy of Sciences

Manipulation of spin states via purely electric means forms the research branch "all-electric spintronics".In this paper,we briefly review recent progress relating to the all-electric spintronics,including electric-field control of Rashba spin-orbit coupling,magnetic anisotropy,exchange bias,ferromagnetism,and other forms of magnetoelectric *** focus is given to surface/interface systems,including semiconductor(oxide) heterostructures,magnetic/nonmagnetic surfaces,semiconductor-metal interfaces,and other nanostructures,which can be good candidates for functional materials for spintronic.

关键词： Rashba magnetoelectric effect multiferroic surface interface

Room temperature preparation of highly stable cesium lead halide perovskite nanocrystals by ligand modification for white lightemitting diodes

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Nano Research 2021年第8期14卷 2770-2775页

作者： Yu Zhang Guishun Li Changkun She Shaohua Liu Fangyu Yue Chengbin Jing Ya Cheng junhao chu Engineering Research Center for Nanophotonics and Advanced Instrument of Ministry of Education Key Laboratory of Polar Materials and Devices(Ministry of Education)The Extreme Optoelectromechanics LaboratoryDepartment of MaterialsSchool of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China

The poor stability of halide perovskite nanocrystals(NCs)has severely hindered future practical ***,we proposed a facile and effective ligand modification route to synthesize stable CsPbBr_(3) nanocrystals by introducing a double-terminal ligand,namely 4,4'-Azobis(4-cyanovalericacid)(CA),to replace the conventional oleic acid(OA)ligand at room *** as-synthesized CsPbBr_(3)-CA not only possesses high photoluminescence quantum yield(72%)related to the reduced trap defects,but also shows significantly improved stability exposure to water,ethanol,light,and/or heat benefiting from the CA ligand anchored to NC surfaces *** photoluminescence intensity of CsPbBr_(3)-CA maintains about 80%and 75%of its initial emission intensity after immersed in water or ethanol for 360 min,respectively,whereas that of the CsPbBr_(3)-OA was quenched completely within a few ***,an all-inorganic white light-emitting diode(LED)covered 126%National Television System Committee(NTSC)standard and 92%Rec.2020 standard was fabricated by combining the green CsPbBr_(3)-CA and commercial red-emitting K2SiF6:Mn4+(KSF)phosphors onto a blue LED ***,the presented work initiates the development of the room temperature preparation of high quality CsPbBr_(3) and shows prospect for next-generation displays.

关键词： perovskite nanocrystals ligand modification stability white light-emitting diode

Spatial-spectral identication of abnormal leukocytes based on microscopic hyperspectral imaging technology

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Journal of Innovative Optical Health Sciences 2020年第2期13卷 44-56页

作者： Xueqi Hu Jiahua Ou Mei Zhou Menghan Hu Li Sun Song Qiu Qingli Li junhao chu Shanghai Key Laboratory of Multidimensional Information Processing East China Normal University Shanghai 200241 P.R.China

Screening and diagnosing of abnormal Leukocytes are crucial for the diagnosis of immune diseases and Acute Lymphoblastic Leukemia(ALL).As the deterioration of abnormal leukocytes is mainly due to the changes in the chromatin distribution,which signicantly affects the absorption and reflection of light,the spectral feature is proved to be important for leukocytes classication and *** paper proposes an accurate identication method for healthy and abnormal leukocytes based on microscopic hyperspectral imaging(HSI)technology which combines the spectral *** segmentation of nucleus and cytoplasm is obtained by the morphological watershed ***,the spectral features are extracted and combined with the spatial *** on this,the support vector machine(SVM)is applied for classication ofve types of leukocytes and abnormal *** with different classication methods,the proposed method utilizes spectral features which highlight the differences between healthy leukocytes and abnormal leukocytes,improving the accuracy in the classication and identication of *** paper only selects one subtype of ALL for test,and the proposed method can be applied for detection of other leukemia in the future.

关键词： Leukocyte microscopic hyperspectral imaging nucleus segmentation Acute Lymphoblastic Leukemia.