Atomic excitations in sputtering studied with group two element targets

Solid targets of Be, Mg, Zn, and Cd have been bombarded with 50 keV Ar⁺ ions. The relative excitation of the lowest-lying excited levels in sputtered neutrals and singly-charged ions have been measured using optical spectrometry. It is found that singly-charged ions are excited much more efficiently than neutral atoms. This is discussed, and it is concluded that atomic excitation in sputtering results from electron pick-up to excited states in initially ionized atoms rather than from inelastic atom-atom or electron-atom collisions.     

Atomic collective excitations in liquid lead

The atomic dynamics of liquid lead at the temperature T = 600 K has been simulated on the basis of the embedded atom model potential (the “embedded” atom model making it possible to effectively take into account the many-particle interactions) in order to study the mechanisms of formation of the atomic collective excitations. Spectra of the dynamic structure factor S(k, ω) and the spectral densities of the time correlation functions of the longitudinal \(\tilde C_L\) (k, ω) and transverse \(\tilde C_T\) (k, ω) currents have been calculated for the wavenumber region 0.11 Å^?1 ≤ k ≤ 2.01 Å^?1. It has been established that the dynamics of density fluctuations is characterized by two dispersion “acoustic-like” branches of the longitudinal and transverse polarization.     

Surface oxidation kinetics of sputtering targets

Films of compounds can be deposited by sputtering a metal or alloy target in an atmosphere containing a suitable reactive gas. Both Al and 90 : 10 In : Sn targets have been sputtered in argon/oxygen mixtures to obtain Al₂O₃ and indium tin oxide films. The experiments were carried out in a planar magnetron sputtering system with both dc and rf excitation. To investigate the kinetics of the reactive sputtering process, the time dependence of the total gas pressure was measured after a change in oxygen flow rate or sputtering power; a capacitance manometer gave accurate and reproducible results. There were simultaneous changes in the rf matching conditions when rf excitation was used. These changes can be attributed to the formation of an oxide on the target surface. The time dependence of the oxygen pressure measured for the Al and In : Sn targets have been used to compare various models of the reactive sputtering process. Fitting of the experimental values to these models yields values of the equilibrium oxide thickness on the target and these have been compared with measured values. For rf sputtering of an Al target at 500 W with flow rates of $\text{3}\text{ml}\text{min}$ and $\text{2.2}\text{ml}\text{min}$ for argon and oxygen respectively, both the calculated and the measured value of the oxide thickness is 100 nm.     

Flavor altering excitations of composite fermions

Past theoretical studies have considered excitations of a given flavor of composite fermions across composite-fermion quasi-Landau levels. We show that in addition there exists a ladder of flavor changing excitations in which composite fermions are partially dissociated by a removal of some or all of their vortices, and suggest that these are relevant to the intriguing experimental discovery of Hirjibehedin et al. [Phys. Rev. Lett. 91, 186802 (2003)] of coexisting excitation modes of composite fermions of different flavors in the filling factor range 1/3 > nu > or = 1/5.     

Atomic NOON state generation in distant cavities by virtual excitations

A general scheme of generating NOON states of virtually-excited 2N atoms is proposed. The two cavities are fibre-connected with N atoms in each cavity. Although we focus on the case of N = 2, the system can be extended to a few atoms with N 〉2. It is found that all 2N atoms can be entangled in the form of NOON states if the atoms in the first cavity are initially in the excited states and atoms in the second cavity are all in the ground states. The feasibility of the scheme is carefully discussed, it shows that the NOON state with a few atoms can be generated with good fidelity and the scheme is feasible in experiment.     

A comparison of gas-phase,plasma, sputtering and beam-foil excitations

A comparison of relative populations of ZnI and ZnII levels excited in equilibrium plasma, sputtering, gas-phase single collision, and beam foil sources is presented, and includes data on the first reported excitation studies under single collision conditions for a (transition metal atom)-(transition metal ion) interaction. A search for continuum emission from atomic chromium, like that seen during sputtering of chromium metal, produced a negative result.     

Interaction of anomalous muonium with electronic excitations in Si studied by longitudinal field μSR

We report longitudinal muon spin relaxation measurements in Si doped with phosphorus below room temperature. The data can be described qualitatively in a model where bond-centered muonium is undergoing spin exchange interactions below 150 K. Above this temperature, charge state cycling becomes important.This work is partially supported by the National Sciences and Engineering Research Council of Canada.     

Relaxation of electronic excitations in wide-gap crystals studied by femtosecond interferometry technique

Time-resolved interferometry with a 100-fs temporal resolution was applied for the first time to studying the relaxation of electronic excitations in complex oxides, namely, tungstates CDWO₄ with a crystal lattice of the wolframite-type and CaWO₄ with a scheelite-type lattice. Two stages of charge carrier relaxation, namely, very fast carrier trapping in 200 fs resulting in self-trapped exciton formation and a relatively slow picosecond relaxation process probably due to configurational relaxation within the oxyanion molecule and modification of the surrounding lattice, are revealed in tungstate crystals. Corresponding models of self-trapped exciton creation in tungstate crystals are discussed. The text was submitted by the authors in English.     

Atomic structure of boron nitride nanotubes with an armchair-type structure studied by HREM

Hexagonal networks of boron nitride (BN) nanotubes were investigated by high-resolution electron microscopy (HREM) and image simulation. From HREM images, lattice planes of {002} and hexagonal rings of a BN nanotube were confirmed. Asymmetrical layer arrangements were found, and a structure model for double-walled BN nanotube with an armchair-type structure has been proposed.     

Fe-Ni-Zr films with large perpendicular anisotropy deposited on PEN tape by facing targets sputtering

One of the origins of perpendicular magnetic energy of Fe-Zr films may be attributed to the structural inhomogeneity of Fe-rich alloy crystallites in a Fe-Zr amorphous matrix. Fe-Ni-Zr films deposited on PEN tape substrates at about 90°C exhibited large K_u with appropriately large 4πM_s suitable for flexible recording media.     

Computer simulation of back sputtering and ion penetration into polycrystalline targets

Pramana - In the present work computer simultations of the back sputtering of low energy neon ions with low impact parameter and the penetration of the same for higher values of the impact...     

Localized electronic excitations in NiO studied with resonant inelastic X-Ray scattering at the Ni M threshold: evidence of spin flip

We studied the neutral electronic excitations of NiO localized at the Ni sites by measuring the resonant inelastic x-ray scattering (RIXS) spectra at the Ni M2,3 edges. The good energy resolution allows an unambiguous identification of several spectral features due to excitations. The dependence of the RIXS spectra on the excitation energy gives evidence of local spin flip and yields a value of 125 +/- 15 meV for the antiferromagnetic exchange interaction. Accurate crystal field parameters are also obtained.     

Study of the physical sputtering of a carbon-ceramic composite by ion bombardment

The results of experimental study and computer simulation of SG-P-0.1 carbon-ceramic composite sputtering under 30 keV Ar⁺ ion irradiation at normal incidence are presented. A comparison with the simulation data shows that taking into account the nanometric wave-like relief well describes an approximately threefold increase in the sputtering yield observed in the experiment in comparison to the smooth surface calculation.     

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探讨了矩形平面、圆形平面和圆柱管这三种常见磁控溅射源的靶材极限利用率的理论计算方法,推出了利用率的近似计算公式,分析了影响利用率的因素。跑道刻蚀形状(宽度和收缩系数)强烈影响平面类静态靶的极限利用率。旋转磁场圆柱管靶材的极限利用率主要决定于靶的自身几何尺寸(壁厚、长度和管径),与跑道的刻蚀形状(即外界的物理因素)几乎没有关系。     

Atomic N00N state generation in distant cavities by virtual excitations

A general scheme of generating N00N states of virtually-excited 2N atoms is proposed. The two cavities are fibre-connected with N atoms in each cavity. Although we focus on the case of N=2, the system can be extended to a few atoms with N>2. It is found that all 2N atoms can be entangled in the form of N00N states if the atoms in the first cavity are initially in the excited states and atoms in the second cavity are all in the ground states. The feasibility of the scheme is carefully discussed, it shows that the N00N state with a few atoms can be generated with good fidelity and the scheme is feasible in experiment.