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Unravelling a solution-based formation of single- crystalline kinked wurtzite nanowires： The case of MnSe

Nano Research 2017年第7期10卷 2311-2320页

作者： Xinyi Yang Bo Zhou Chuang Liu Yongming Sui Guanjun Xiao Yingjin wei Xin Wang Bo Zou State Key Laboratory of Superhard Materials Jilin University Changchun 130012 China Laboratory of Physics and Technology for Advanced Barteries (Ministry of Education) Jilin University Changchun 130012 China College of Physics Jilin University Changchun 130012 China

The search for a novel strategy to sculpt semiconductor nanowires （NWs） at the atomistic scale is crucial for the development of new paradigms in optics, electronics, and spintronics. Thus far, the fabrication of single-crystalline kinked semiconductor NWs has been achieved mainly through the vapor-liquid-solid growth technique. In this study, we developed a new strategy for sculpting single-crystalline kinked wurtzite （WZ） MnSe NWs by triggering the nonpolar axial-oriented growth, thereby switching--at the atomistic scale---the NW growth orientation along the nonpolar axes in a facile solution-based procedure. This presents substantial challenges owing to the dominant polar c axis growth in the solution-based synthesis of one-dimensional WZ nanocrystals. More significantly, the ability to continuously switch the nonpolar axial-growth orientation allowed us to craft the kinking landscape of types 150°, 120°, 90°, and 60°. A probabilistic analysis of kinked MnSe NWs reveals the correlations of the synergy and interplay between these two sets of nonpolar axial growth-orientation switching, which determine the actual kinked motifs. Furthermore, discriminating the side-facet structures of the kinked NWs significantly strengthened the spatially selected interaction of Au nanoparticles. We envisage that such a facile solution-based strategy can be useful for synthesizing other single-crystalline kinked WZ-type transition-metal dichalcogenide NWs to develop novel functional materials with finely tuned properties.

关键词： kinked nanowires single-crystalline nonpolar axial growth wurtzite MnSe

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Electronic structure and optical properties of the scintillation material wurtzite ZnS(Ag)

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Nuclear Science and Techniques 2017年第3期28卷 35-41页

作者： Dong-Yang Jiang Zheng Zhang Rui-Xue Liang Zhi-Hong Zhang Yang Li Qiang Zhao Xiao-Ping Ouyang Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy School of Nuclear Science and EngineeringNorth China Electric Power University Beijing 102206China School of Electrical and Electronic Engineering North China Electric Power University Beijing 102206 China Northwest Institute of Nuclear Technology Xi’an 710024China School of Materials Science and Engineering Xiangtan University Xiangtan 411105 China

In order to investigate the effect of Ag doping(ZnS(Ag)) and Zn vacancy(V_(Zn)) on the alpha particle detection performance of wurtzite(WZ) ZnS as a scintillation cell component, the electronic structure and optical properties of ZnS, ZnS(Ag), and V_(Zn)were studied by firstprinciple calculation based on the density functional theory. The results show that the band gaps of ZnS, ZnS(Ag),and V_(Zn)are 2.17, 1.79, and 2.37 eV, respectively. Both ZnS(Ag) and V_(Zn)enhance the absorption and reflection of the low energy photons. A specific energy, about 2.9 eV,leading to decrease of detection efficiency is observed. The results indicate that Ag doping has a complex effect on the detection performance. It is beneficial to produce more visible light photons than pure WZ ZnS when exposed to the same amount of radiation, while the increase of the absorption to visible light photons weakens the detection performance. Zn vacancy has negative effect on the detection performance. If we want to improve the detection performance of WZ ZnS, Ag doping will be a good way,but we should reduce the absorption to visible light photons and control the number of Zn vacancy rigorously.

关键词： wurtzite ZnS Electronic structure Optical properties First-principle

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Binding energies of impurity states in strained wurtzite GaN/Al_xGa_(1-x)N heterojunctions with finitely thick potential barriers

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Chinese Physics B 2014年第6期23卷 440-445页

作者：冯振宇班士良朱俊 College of Physical Science and Technology Inner Mongolia University

Ground state binding energies of donor impurities in a strained wurtzite GaN/AlxGal_xN heterojunction with a po- tential barrier of finite thickness are investigated using a variational approach combined with a numerical computation. The built-in electric field due to the spontaneous and piezoelectric polarization, the strain modification due to the lattice mismatch near the interfaces, and the effects of ternary mixed crystals are all taken into account. It is found that the binding energies by using numerical wave functions are obviously greater than those by using variational wave functions when impurities are located in the channel near the interface of a heterojunction. Nevertheless, the binding energies using the former functions are obviously less than using the later functions when impurities are located in the channel far from an interface. The difference between our numerical method and the previous variational method is huge, showing that the former should be adopted in further work for the relevant problems. The binding energies each as a function of hydrostatic pressure are also calculated. But the change is unobvious in comparison with that obtained by the variational method.

关键词： wurtzite GaN/AlxGa1-xN heterojunction impurity state binding energy

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Surface saturation control on the formation of wurtzite polytypes in zinc blende SiC nanofilms grown on Si-(100) substrates

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Chinese Physics B 2013年第8期22卷 542-546页

作者：刘兴昉孙国胜刘斌闫果果关敏张杨张峰董林郑柳刘胜北田丽欣王雷赵万顺曾一平 Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences

We investigate the formations of wurtzite （WZ） SiC nano polytypes in zinc blende （ZB） SiC nanofilms hetero-grown on Si-（100） substrates via low pressure chemical vapor deposition （LPCVD） by adjusting the Si/C ratio of the introduced precursors. Through SEM, TEM, and Raman characterizations, we find that the nanofilms consist of discrete WZ SiC nano polytypes and ZB SiC polytypes composed of WZ polytypes （WZ ＋ ZB） and disordered ZB SiC polytypes, respectively, according to Si/C ratios of 0.5, 1.5, and 3. We attribute the WZ polytype formation to being due to a kinetic mechanism based on the Si/C surface saturation control.

关键词： SiC wurtzite zinc blende nanofilm

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First-Principles Study of the γ Angle Deformation Path in the wurtzite-to-Rocksalt Phase Transition in Aluminum Nitride

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Chinese Physics Letters 2010年第9期27卷 175-178页

作者：蔡影祥徐瑞 Department of Physics Nanchang University Nanehang 330031 State Key Laboratory of Metastable Mater-ials Science and Technolo-gy Yanshan University Qinhuangdao 066004

A new transition path （γ angle deformation path） is put forward and used to characterize the wurtzite-rocksalt transition in AlN. The enthalpy surface and the contour plot of enthalpy difference at equilibrium pressure are obtained by first-principles pseudopotential method within the generalized gradient approximation. The phase transition is needed to overcome two barriers and a metaphase arises between them. The total barrier height is 0.26eV. The pressure region of the phase transition is estimated to be 13.9-23.5 GPa, in which the experimental result is well located. Along the least barrier path, the changes of density of states and the fields of charge density difference are investigated. The similarities and differences between γ angle deformation path and the orthorhombic deformation path are analyzed.

关键词： DEFORMATIONS (Mechanics) wurtzite ROCK salt PHASE transformations (Physics) ALUMINUM nitride ENTHALPY

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Mechanical and Vibrational Properties of ZnS with wurtzite Structure： A First-Principles Study

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Chinese Physics Letters 2014年第10期31卷 100-103页

作者：虞游陈春林赵国栋郑小林朱兴华 College of Optoelectronic Technology Chengdu University of Information Technology Chengdu 610225

We perform a first-principles study of the mechanical and vibrational properties of ZnS with a wurtzite structure. The calculated elastic constants by using a pseudopotential plane-wave method agree well with the experimental data and with the previous theoretical works. Based on the elastic constants and their related parameters, the crystal mechanical stability is discussed. Calculations of the zone-center optical-mode frequencies including longitudinal-optical/transverse-optical splitting, by using the density functional perturbation theory, are reported. All optical modes are identified, especially B1 modes, and agree with Raman rneasurements.

关键词： ZINC sulfide MECHANICAL behavior of materials wurtzite ELASTIC constants DENSITY functional theory PERTURBATION (Mathematics) PSEUDOPOTENTIAL method

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A COMPREHENSIVE INVESTIGATION ON A PECULIAR DEFECT IN wurtzite GaN FILM

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Acta Metallurgica Sinica(English Letters) 1999年第4期12卷 327-333页

作者： S.Q.Wang1 ,2) and H.Q.Ye1) 1) Laboratory of Atomic Imaging of Solids,Institute of Metal Research , The Chinese Academy of Sciences, Shenyang 110015 ,China 2)Department of Materials Science and Metallurgy , University of Cambridge, Cambridge CB2 3QZ, UK

Apeculiar crystal defect was observed by experiment of high resolution electron microscopy( HREM) .It wasidentifiedtoformed bytwothreading dislocationsand asegmentof(11 20) domain boundary. An atomicstructure model was proposed for the anomalous defect. Theresultofthe weak beam experimentofelectron microscopeaffirmedthesuggested *** GaN(11 2 0) domain boundaries werestudied by Molec ular Dynamicscalculations. Thetheoreticalresultsshowedthatthelike atom bonding domain boundary, whichcomposesthe main partofthe peculiar defect, has much higher formationenergy than itcounterpartof unlike atom bonding domain boundary. Theoutcome providesanotherevidenceforthesuggested model.

关键词： HREM weak beam electron microscopy crystal defect wurtzite GaN molecular dynamics

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Raman scattering study on anisotropic property in wurtzite 4H-Si C

Raman scattering study on anisotropic property in wurtzite 4...

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第十九届全国光散射学术会议

作者： Dishu Zhao Fangze Wang Lingyu Wan Qingyi Yang Zhe Chuan Feng Laboratory of optoelectronic materials ＆ detection technology Guangxi Key Laboratory for the Relativistic Astrophysics College of Physics Science ＆ Technology Guangxi University

＜正＞Silicon carbide（Si C）is a wide bandgap semiconductor having high critical electric field strength,making it especially attractive for high-power and high-temperature *** development of Si C devices relies

关键词：关键词 4H-SiC Raman anisotropic property wurtzite

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CdS quantum dot aerogels for photocatalytic hydrogen evolution

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Nano Research 2024年第12期17卷 10292-10301页

作者： Vinicius Alevato Daniel Streater Cole Premtaj Jier Huang Stephanie L.Brock Department of Chemistry Wayne State UniversityDetroitMI 48202USA Department of Chemistry Marquette UniversityMilwaukeeWI 53201USA Department of Chemistry&Shiller Institute for Integrated Science and Society Boston CollegeBostonMA 02467USA

CdS quantum dots(QDs)have been extensively studied as photocatalysts and sensitizers for visible-light-driven water ***,their efficiencies are limited by the need to accumulate sufficient redox equivalents to produce_(H2)and consequent photocorrosion associated with slow hole-transfer *** address these limitations,we report the formation of CdS QD assemblies(aerogels,AGs)capable of facilitating energy/charge transport between individual QDs,and evaluate their performance as photocatalysts for hydrogen evolution as a function of structure,wurtzite(w-)***(zb-),and different annealing *** formation of AGs from QDs resulted in increased rates of_(H2)production under visible light illumination:from 1458(QD)to 6650(AG)μmol_(H2)·h^(-1)·g^(-1)on zbCdS and from 1221(QD)to 3325(AG)μmol_(H2)·h^(-1)·g^(-1)on *** is attributed to exciton delocalization between adjacent QDs facilitating charge/energy *** processing of CdS AGs up to 250℃ improved their activity,increasing the degree of exciton delocalization,while annealing them to 300℃ caused sintering of the primary QD particles within the AGs and a decrease in activity associated with loss in surface *** best photocatalyst,zbCdS AG annealed at 250℃,had an average_(H2)production rate of 13,604±2017μmol_(H2)·h^(-1)·g^(-1),an apparent quantum yield of 2.8%at 425±12.5 nm,and was stable for 2 h before beginning to deactivate due to *** study confirms the potential of CdS AGs as matrixes for the design of more active and stable composite photocatalysts for water splitting.

关键词： sol-gel chemistry photocorrosion apparent quantum yield wurtzite zinc blende

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Synthesis and Growth Mechanism： A Novel Fishing Rod-Shaped GaN Nanorods

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Chinese Physics Letters 2014年第5期31卷 114-117页

作者：张士英修向前华雪梅谢自力刘斌陈鹏韩平陆海张荣郑有炓 Key Laboratory of Advanced Photonic and Electronic Materials School of Electronic Science and Engineering Nanjing University Nanjing 210093 College of Optoelectronics-Engineering Zaozhuang University Zaozhuang 277160

A novel fishing rod-shaped GaN nanorod is successfully fabricated through a new method by using the two-step growth technology. This growth method is applicable to continuous synthesis and is able to produce a large number of single-crystalline GaN nanorods with a relatively high purity and at a low cost. X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy are used to characterize the as- synthesized nanorods. The results show that most of the nanorods consist of a main rod and a top curved thread. It is single-crystal GaN with hexagonal wurtzite structure. The representative photoluminescence spectrum at room temperature exhibits a strong UV light emission band centered at 370.8nm. Furthermore, a possible two-stage growth mechanism of the fishing rod-shaped GaN nanorod is also briefly discussed.

关键词： NANORODS GALLIUM nitride X-ray diffraction SCANNING electron microscopy TRANSMISSION electron microscopy wurtzite

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