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Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires

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Nano Research 2021年第11期14卷 4087-4092页

作者： Lukas Hrachowina Xianshao Zou Yang Chen Yuwei Zhang Enrique Barrigón Arkady Yartsev Magnus T.Borgström NanoLund Lund UniversityBox 11822100LundSweden divison of solid state physics Lund UniversityBox 11822100LundSweden divison of Chemical physics Lund UniversityBox 12422100LundSweden Toyota Technological Institute NagoyaAichi 468-8511Japan

Nanowires require surface passivation due to their inherent large surface to volume ratio. We investigate the effect of embedding InP nanowires in different oxides with respect to surface passivation by use of electron beam induced current measurements enabled by a nanoprobe based system inside a scanning electron microscope. The measurements reveal remote doping due to fixed charge carriers in the passivating PO_(x)/Al_(2)O_(3) shell in contrast to results using SiO_(x). We used time-resolved photoluminescence to characterize the lifetime of charge carriers to evaluate the success of surface passivation. In addition, spatially resolved internal quantum efficiency simulations support and correlate the two applied techniques. We find that atomic-layer deposited PO_(x)/Al_(2)O_(3) has the potential to passivate the surface of InP nanowires, but at the cost of inducing a field-effect on the nanowires, altering their electrostatic potential profile. The results show the importance of using complementary techniques to correctly evaluate and interpret processing related effects for optimization of nanowire-based optoelectronic devices.

关键词： InP nanowires oxides MOVPE electron beam induced current(EBIC) time-resolved photoluminescence(TRPL) field-effect

Generation of spectrally stable 6.5-fs visible pulses via filamentation in krypton

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High Power Laser Science and Engineering 2016年第2期4卷 75-79页

作者： Keisuke Kaneshima Kengo Takeuchi Nobuhisa Ishii Jiro Itatani The Institute for solid state physics The University of Tokyo

We produced 5-μJ, 6.5-fs visible pulses at a repetition rate of 1 kHz using filamentation in a gas cell filled with krypton followed by spectral selection and phase compensation by a combination of dielectric mirrors. The visible pulses have a smooth spectrum from 520 to 650 nm with a shot-to-shot stability in each spectral component of better than 2%(standard deviation). This pulse compression scheme is simple and robust, and can be easily integrated into intense ultrashort-pulse laser systems.

关键词： filamentation ultrafast spectroscopy ultrashort visible pulses

Effective permittivity and permeability of one-dimensional dielectric photonic crystal within a band gap

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Chinese physics B 2008年第7期17卷 2544-2552页

作者：郭继勇陈鸿李宏强张冶文 Pohl Institute of solid state physics Tongji University

We take a finite dielectric photonic crystal as a homogeneous slab and have extracted the effective parameters. Our systematic study shows that the effective permittivity or permeability of dielectric photonic crystal is negative within a band gap region. This means that the band gap might act as ε-negative materials （ENMs） with ε 〈 0 and μ 〉 0, or μ-negative materials （MNMs） with ε 〉 0 and μ 〈 0. Moreover the effective parameters sensitively rely on size, surface termination, symmetry, etc. The effective parameters can be used to design full transmission tunnelling modes and amplify evanescent wave. Several cases are studied and the results show that dielectric photonic band gap can indeed mimic a single negative material （ENM or MNM） under some restrictions.

关键词： photonic crystal negative permittivity negative permeability

Simulation of water potential for the electronic structure of serine

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Chinese physics B 2009年第5期18卷 1968-1978页

作者：王兴荣郑浩平 Pohl Institute of solid state physics Tongji University

First-principles, all-electron, ab initio calculations have been performed to construct an equivalent water potential for the electronic structure of serine （Ser） in solution. The calculation is composed of three steps. The first step is to search for the configuration of the Ser _ nH2O system with a minimum energy. The second step is to calculate the electronic structure of Ser with the water molecule potential via the self-consistent cluster-embedding method （SCCE）, based on the result obtained in the first step. The last step is to calculate the electronic structure of Set with the dipole potential after replacing the water molecules with dipoles. The results show that the occupied states of Ser are raised by about 0.017 Ry on average due to the effect of water. The water effect can be successfully simulated by using the dipole potential. The obtained equivalent potential can be applied directly to the electronic structure calculation of protein in solution by using the SCCE method.

关键词： serine electronic structure water self-consistent cluster-embedding calculation

Design and Analysis of Microstrip Multi-Channeled Filter Using Photonic Crystal Branchy Defect

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Journal of Rare Earths 2006年第z1期24卷 136-139页

作者： Li Yunhui Jiang Haitao He Li Li Hongqiang Zhang Yewen Chen Hong Pohl Institute of solid state physics Tongji University Shanghai 200092 China Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China

A multi-channeled filter based on branchy defect in a microstrip photonic crystal was proposed. By introducing a branchy structure across the defect region, multiple defect modes will appear inside the photonic gap, leading to the multi-channeled filtering phenomenon. In comparison with the conventional multi-channeled filters, the proposed structure is more compact and tunable as far as the device volume and fabrication are concerned. The microwave experiment results are found in agreement with simulation results.

关键词： photonic crystals defect mode multi-channeled filter

Investigation of the free volume and ionic conducting mechanism of poly(ethylene oxide)-LiClO_4 polymeric electrolyte by positron annihilating lifetime spectroscopy

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Chinese physics B 2012年第10期21卷 478-484页

作者：龚静宫振丽闫晓丽高舒张忠良王波 School of physics and Key Laboratory of Nuclear solid state physics Wuhan University

The positron annihilation lifetime and ionic conductivity are each measured as a function of organophilic rectorite（OREC） content and temperature in a range from 160 K to 300 *** to the variation of ortho-positronium（o-Ps） lifetime with temperature,the glassy transition temperature is *** continuous maximum entropy lifetime（MELT） analysis clearly shows that the OREC and temperature have important effects on o-Ps lifetime and free volume *** experimental results show that the temperature dependence of ionic conductivity obeys the Vogel-Tammann-Fulcher（VTF） and Williams-Landel-Ferry（WLF） equations,implying a free-volume transport mechanism.A linear least-squares procedure is used to evaluate the apparent activation energy related to the ionic transport in the VTF equation and several important parameters in the WLF *** is worthwhile to notice that a direct linear relationship between the ionic conductivity and free volume fraction is established using the WLF equation based on the free volume theory for nanocomposite electrolyte,which indicates that the segmental chain migration and ionic migration and diffusion could be explained by the free volume theory.

关键词： positron free volume polymeric electrolyte ionic conduction

Influence of Dzyaloshinskii-Moriya and Kaplan-Shekhtman-Entinwohlman-Aharony superexchange interactions on ground state properties of the one-dimensional spin-Peilers model in open chain

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Chinese physics B 2010年第11期19卷 637-640页

作者：刘海莲黄仙山王治国石云龙 School of Mathematics and physics Anhui University of Technology Institute of solid state physics Shanxi Datong University Pohl Institute of solid state physics Tongji University

The effects of the Dzyaloshinskii Moriya （DM） and the Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） superexchange interactions on the ground state properties of the one-dimensional spin-Peilers system in open chain are studied by using the Lanczos numerical method. The study concentrates mainly on the influence of systemic dimerisation in open chain. The results show that systemic ground state energy density varies with dimerisation parameter 5 in different DM interactions, and there exists a special point 5c where the DM interaction has no influence on the systemic dimerisation, no matter whether the DM interaction is relative or irrelative to systemic dimerisation （η= 1 or η=0）. The KSEA interaction has no fixed special point, but the points of intersection are dense relatively in a certain numberical value range, and sparse in other numberical value ranges. So we can conclude that the antisymmetric anisotropy DM interaction differs from the symmetric anisotropy KSEA interaction, but they are analogous in the sense of the influence of systemic dimerisation in open chain.

关键词： dimerisation Dzyaloshinskii-Moriya interaction Kaplan-Shekhtman-Entinwohlman Aharony interaction open chain

Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

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中国有色金属学会会刊：英文版 2003年第6期13卷 1394-1400页

作者：吴玉程吴侠李广海张立德 Faculty of Materials science and Engineering Institute of solid state physics

In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica, the silica was prepared by sol-gel technique, leading to an amorphous solid with mesoporosity, and the pore size distribution is narrow, centered at 35 nm. The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen. The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination, resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature. The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

关键词：二氧化硅钯纳米材料复合材料煅烧加载

A molecular dynamics simulation of segregation behaviours of horizontally vibrated binary granular mixture

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Chinese physics B 2010年第5期19卷 460-465页

作者：夏继宏尤玉伟汪盼盼王炜路刘长松 Key Laboratory of Materials physics Institute of Solid State PhysicsChinese Academy of Sciences

This paper performs the two-dimensional, soft-sphere molecular dynamics simulations to study the granular segregation in a binary granular mixture with the same size but different density in the container with the sawtooth base under horizontal vibration. The segregation phase diagram is presented in the acceleration-frequency space. When the acceleration is high enough to result in relative motions of the particles, the system can be in various states （mixed state, vertical and horizontal segregation state）, which depend on both acceleration and frequency. Due to the sawtooth base there is stratified flow effect besides density effect. The density effect raises the light particles. The stratified flow drives the particles in the upper levels to the right and the particles in the lower particles to the left, resulting in the appearance of the left segregation state. The left segregation state can be changed to the right segregation by changing the shape of the sawtooth. As the vibration frequency increases, the stratified flow effect becomes weaker and weaker, so at high vibration frequencies the vertical segregation state appears instead of the left segregation state.

关键词： granular systems segregation molecular dynamics methods