Nature of the Stranski-Krastanow transition during epitaxy of InGaAs on GaAs

We report first quantitative measurements by energy-selected imaging in a transmission electron microscope of In segregation within an uncapped islanded In0.25Ga0.75As layer grown epitaxially on GaAs. This layer has the lowest In concentration at which islanding occurs and, then, only after a flat approximately 3 nm alloy layer has been formed. In buildup by segregation at the surface of this initial flat layer is considered the driving force for islanding and, importantly, the segregation process introduces the characteristic delay seen before the Stranski-Krastanow transition. We observe strong inhomogeneous In enrichment within the islands (up to x(In) approximately 0.6 at the apex) and a simultaneous In depletion in the remaining flat layer.     

Structural and size evolution of indium nanoparticles embedded in aluminum synthesized by ion implantation

The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined as a function of annealing time in a temperature range between 423 K and 453 K. The structural transition of In nanoparticles with the crystallographic orientation In(200)[002] Al(200)[002] is observed to change into In(111)[110] Al(002)[110] with a critical particle radius between 2.3 nm and 2.6 nm. In addition, the growth of In nanoparticles in the annealing process is evidently governed by the diffusion limited Ostwald ripening. By further analyzing the experimental data, values of diffusion coefficient and activation energy are obtained.     

铟磷共掺杂p型氧化锌薄膜形成机理和性质

利用射频磁控溅射在石英衬底上生长出铟磷共掺氧化锌薄膜(ZnO ∶ In,P),所用靶材为掺杂五氧化二磷(P₂O₅)和氧化铟(In₂O₃)的氧化锌(ZnO)陶瓷靶,掺杂质量分数分别为1.5%和0.3%,溅射气体为Ar和O₂的混合气体。原生ZnO薄膜是绝缘的, 600 ℃退火5 min后导电类型为n型,而800 ℃退火5 min后为p型。p型ZnO薄膜的电阻率、载流子浓度和霍尔迁移率分别为12.4 Ω·cm, 1.6×10¹⁷ cm^-3 和3.29 cm²·V^-1·s^-1。X射线衍射测量结果表明所有样品都只有(002)衍射峰,并与相同条件下生长的未掺杂ZnO相比向大角度方向偏移,意味着In和P都占据Zn位。XPS测试结果表明在共掺ZnO薄膜中P不是取代O而是取代Zn。因此,铟磷共掺ZnO薄膜中,In和P都取代Zn,并且P_Zn与2个锌空位(V_Zn)形成P_Zn-2V_Zn复合受主,薄膜表现为p型。     

单畴的单原子In纳米线阵列的制备与研究

利用Si（001）向［110］方向偏4°角的斜切表面作为衬底，成功地制备了分布均匀的单畴的单原子In链阵列.扫描隧道显微镜分析表明，沉积的In原子优先吸附在台面上沿着台阶内边缘的位置，并在两个Si的二聚体链之间形成稳定的In二聚体.In二聚体组成直的单原子链，其生长机理与Car提出的“表面聚合反应”相一致.另外，衬底具有非常窄的台面和双原子层台阶边的特殊结构是形成单畴的单原子链的关键. 关键词： 铟单原子链 硅邻近面 扫描隧道显微镜     

Preparation of In2S3 nanopraricle by ultrasonic dispersion and its tribology property

In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.     

Reestablishment of an Unknown State and Its Orthogonal Complement State with Assistance

In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is performed between Alice (a sender) and Bob (a receiver) through a nonmaximally entangled quantum channel. In the process of teleportation, Alice performs nonmaximally entangled state measurement. In the second stage of the protocol, Victor(a state preparer) disentangles leftover nonmaximally entangled states by a single-particle measurement. With the assistance of Victor Alice can reestablish the original state or produce its orthogonal state.     

Topological instability along filamented invariant surfaces

In dynamical systems with a zero Lyapunov exponent, weak mixing can be governed by a specific topological structure of some surfaces that are invariant with respect to particle dynamics. In particular, when the genus of the invariant surfaces is more than one, they may have weak mixing and the corresponding fractional kinetics. This possibility is demonstrated by using a typical example from plasma physics, a three-dimensional resistive pressure-gradient-driven turbulence model. In a toroidal geometry and with a low-pressure gradient, this model shows the emergence of quasicoherent structures. In this situation, the isosurfaces of the velocity stream function have a web structure with filamentary surfaces emerging from the outer region of the torus and covering the inner region. The filamentary surfaces can result in stochastic jets of particles that cause a "topological instability." In such a situation, particle transport along the surfaces is of the anomalous superdiffusion type.     

Design study of a L-band photocathode RF injector

In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used for THz radiation. In this test facility, a L-band photocathode RF injector is needed. In this paper, we give the physical design of the L-band photocathode RF injector for the test facility.     

Design study of a L-band photocathode RF injector

In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used for THz radiation. In this test facility, a L-band photocathode RF injector is needed. In this paper, we give the physical design of the L-band photocathode RF injector for the test facility.     

Neutrino helicity flip in a curved space-time

In Minkowskian spaces, the helicity of a massless fermion is a conserved quantity. In principle, this property may not hold when gravitational effects are not neglected. In this context, this work proves that the helicity of a massless neutrino is not conserved in curved spaces. In order to show this fact, the time variation of the helicity in the Heisenberg picture is calculated. Also, we verify that the differential cross-section due to helicity flip of a massless neutrino in a curved space does not vanish as a result of the coupling between the spin and the curvature of space-time.     

Reestablishment of an Unknown State and Its Orthogonal Complement State with Assistance

In this paper, we propose a protocol where one can realize reestablishment of an unknown state and its orthogonal complement state with a certain probability. In the first stage of the protocol, teleportation is performed between Alice (a sender) and Bob (a receiver) through a nonmaximally entangled quantum channel. In the process of teleportation, Alice performs nonmaximally entangled state measurement. In the second stage of the protocol, Victor (a state preparer) disentangles leftover nonmaximally entangled states by a single-particle measurement. With the assistance of Victor Alice can reestablish the original state or produce its orthogonal state.     

Is the percolation transition of hard spheres a thermodynamic phase transition?

In hard-sphere systems, there is a fluid-solid transition, but no gas-liquid transition. In the fluid region, however, one can find a purely geometric percolation transition, which is studied in detail. The van der Waals model of hard spheres is treated. In this model, a uniform negative background potential is added. This modification does not change the structure, but induces a gas-liquid transition. In fact, percolation and the gas-liquid transition can be related to each other.     

In掺杂h-LuFeO3光吸收及极化性能的第一性原理计算

h-LuFeO3是一种窄带隙铁电半导体材料,已被证明在铁电光伏领域有较好的应用前景.然而,较低的极化强度使光生电子-空穴对复合率大,限制了h-LuFeO3基铁电光伏电池效率的提高.为改善h-LuFeO3的极化强度,提高光吸收性质,本文利用第一性原理计算方法研究了In原子在h-LuFeO3不同位置的掺杂形成能,得到最稳定的掺杂位置,比较了h-Lu1-xInxFeO3(x=0,0.167,0.333,0.667)的带隙、光吸收性能及极化强度等性质.计算结果表明,随着In掺杂比例的增加,h-LuFeO3的晶格常数c/a比不断增大,铁电极化强度得到提高.当In:Lu=2:1时,材料杂质能级出现,Fe-O轨道杂化得到增强,提高了h-LuFeO3的光吸收性能.此工作证明了In掺杂是改善h-LuFeO3极化强度和光吸收系数的有效方法,对铁电光伏性能的提高提供一种新途径.     

Reduction of false alarms in forest fire surveillance using water vapour concentration measurements

In this work a theoretical model to evaluate the capabilities of our lidar system in forest fire detection is reported. In particular, a new idea of minimization of false alarm is shown. In a forest fire, in fact, a lot of ashes and in the first stage a large amount of water vapour are emitted. Measurements of water vapour increase with respect to standard humidity in the atmosphere due to a forest fire event, by means of Raman analysis, permit to minimize the false alarm. A simulation of one case of study permits to estimate the maximum range of detection and minimum sensibility of our lidar system. In this paper the theoretical results are shown.     

Random perculation in metal-Ge mixtures

We have measured the electrical resistivity of InGe, PbGe and A?Ge mixtures co-evaporated onto room temperature substrates, and studied their microstructure by transmission electron microscopy. In InGe and PbGe, where we have observed a random distribution of the constituents, the metal-insulator transition occurs at a metal concentration of about 15% vol., in agreement with random continuum percolation theory. In contrast, A?Ge has a highly regular granular structure and a much higher critical concentration (～ 55%), as do most metal-insulator thin film mixtures.     

Calculation of the temperature distribution on laser-illuminated scanning probe tips

In order to understand the basic process of a laser-illuminated scanning probe tip it is necessary to calculate the temperature distribution in such a geometry. In the first part of this paper the temperature distribution in a laser-heated tip and a semi-infinite metallic sample is solved in a steady-state approach. This is done with the help of the boundary element method. In a second part, the temperature field in a thin metal sheet attached to a semi-infinite dielectric substrate is calculated by applying the Fourier-Bessel transformation method.     

Local effect of electric and magnetic fields on the position of an attached shock in a supersonic diffuser

Effective ways for controlling shock wave configurations by means of external actions are sought. One such way is a local effect of electric and magnetic fields. In this paper, the local effect of external fields is implemented by current localization in a limited region of a diffuser. The experiment is carried out in a diffuser providing the complete internal compression of the gas with a Mach number at the inlet M=4.3. As a working medium, a xenon plasma is used. The plasma flow is formed in a shock tube equipped with an accelerating nozzle. Two ways of current localization are tested. In the first one, the diffuser inlet is a short channel of Faraday generator type. In this case, the ponderomotive force basically decelerates or accelerates the flow depending on the direction of the electric field. In the second way, the current flows through a narrow near-wall region between adjacent electrodes. In this case, the ponderomotive force compresses or expands the gas. In both cases, it is shown that the angle of an attached shock due to MHD interaction can be both decreased and increased. The central problem with the MHD control of shock waves is near-electrode and near-wall phenomena.     

Apparent giant hyperfine anomaly of nuclear levels in the indium isotopes — A puzzle

The magnetic hyperfine fields of In in Fe, Co and Ni were measured by PAC using¹¹⁷In, and by NMR-ON using^114mIn and¹¹⁴In. There is a disparity of about 8% (4%) between the fields derived from PAC on¹¹⁷In (NMR-ON on¹¹⁴In) and the values that have been measured using isomeric 1g_9/2 proton states in^109,111,115In. This is tentatively attributed to a giant hyperfine anomaly.     

Effects of the indium doping on structural and optical properties of CdSe thin films deposited by laser ablation technique

Thin films of n-type CdSe have been grown on a quartz substrate by laser ablating a target obtained by mixing CdSe and metallic In powders. The effects of different doping concentration of In have been investigated. X-ray diffraction spectra show that at low In density only the CdSe lattice is present in the deposited film, whereas CdIn₂Se₄ and InSe compounds are deposited at higher In concentration. Band gap narrowing and band tails are observed in the absorption spectra when the In concentration increases. Photoluminescence spectra show band-band recombinations from 10 K to room temperature. Received 27 September 2002 Published online 11 April 2003 RID="a" ID="a"e-mail: giuseppe.perna@ba.infn.it     

In掺杂ZnO薄膜的制备及其白光发射机理

采用溶胶-凝胶法在Si衬底上制备了本征ZnO薄膜和In:(Zn+In)分别为5%,8%,10%的ZnO薄膜,对薄膜的晶相结构和光电性质进行了表征并在CIE-XYZ表色系统中计算了不同样品的色品坐标.结果表明:In掺入后ZnO薄膜的择优生长方向由(002)面变为(101)面且面间距变小,当In掺杂量为5%时,In原子完全替代Zn原子;薄膜的电阻率随In含量的增加出现先抑后扬的趋势;随着In的掺入光谱的紫外发射峰红移,并在670 nm左右出现一个新的峰值;In:(Zn+In)为5%样品具有白光发射特性.从第一 关键词： In掺杂ZnO薄膜 溶胶-凝胶 色品坐标 白光发射