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The applications of Au thin films and their adhesion layers often suffer from a lack of sufficient information about the chemical states of adhesion layers and about the high-lateral-resolution crystallographic morphology of Au nanograins. Here, we demonstrate the in-depth evolution of the chemical states of adhesive layers at the interfaces and the crystal orientation mapping of gold nanograins with a lateral resolution of less than 10 nm in a Ti/Au/Cr tri-layer thin film system. Using transmission electron microscopy, the variation in the interdiffusion at Cr/Au and Ti/Au interfaces was confirmed. From X-ray photoelectron spectroscopy (XPS) depth profiling, the chemical states of Cr, Au and Ti were characterized layer by layer, suggesting the insufficient oxidation of the adhesive layers. At the interfaces the Au 4f peaks shift to higher binding energies and this behavior can be described by a proposed model based on electron reorganization and substrate-induced final-state neutralization in small Au clusters supported by the partially oxidized Ti layer. Utilizing transmission Kikuchi diffraction (TKD) in a scanning electron microscope, the crystal orientation of Au nanograins between two adhesion layers was non-destructively characterized with sub-10 nm spatial resolution. The results provide nanoscale insights into the Ti/Au/Cr thin film system and contribute to our understanding of its behavior in nano-optic and nano-electronic devices.

Directed self-assembly (DSA), an emerging lithographic technique, has attracted increasing attention as a result of its advantages of low cost, high throughput and convenient processing. However, DSA still presents some challenges, such as the control of defects, the fabrication of complex patterns and pattern registration. In this work, self-assembling morphologies of the lamellar diblock copolymer poly(styrene-b-methyl methacrylate) were investigated to gain a better understanding of the DSA process and to offer some reference for the pattern transfer process. A quantized number of lines was obtained in the directing grooves, although warps and dislocations appeared when the number of lines jumped from n to (n + 1). Gradational variations in line width were observed near the edge of the confining grooves, which shows the lack of uniformity in the patterns. A novel structure model is proposed to interpret this variation in the block copolymer lines. Valuable information and insights are provided for nanowire patterning by DSA in state-of-the-art semiconductor devices.

This paper reports the formation of Ge nanoclusters in a multi-layer structure consisting of alternating thin films of Ge-doped silica glass and SiGe, deposited by plasma-enhanced chemical vapor deposition (PECVD) and post annealed at 1100 °C in N2 atmosphere. We studied the annealed samples by transmission electron microscopy (TEM) and Raman spectroscopy. As-deposited and annealed samples were analyzed by secondary ion mass spectroscopy (SIMS). TEM investigation shows that Ge nanoclusters were formed in the as-deposited SiGe layer and the SiGe layer was transformed into a silicon dioxide layer embedded with Ge nanoclusters after annealing. These nanoclusters are crystalline and varied in size. There were no clusters in the Ge-doped glass layer. Raman spectra verified the existence of crystalline Ge clusters. The positional shift of the Ge vibrational peak with the change of the focus depth indicates that the distribution of the stress applied to the Ge clusters varies with depth. SIMS measurements show clearly the dramatic O increase in the as-deposited SiGe layer after annealing. The creation of Ge nanoclusters by the combination of PECVD and annealing makes possible the application in complicated waveguide components.

We report the nanofabrication and characterization of x-ray transmission gratings with a high aspect ratio and a feature size of down to 65 nm. Two nanofabrication methods, the combination of electron beam and optical lithography and the combination of electron beam, x-ray, and optical lithography, are presented in detail. In the former approach, the proximity effect of electron beam lithography based on a thin membrane of low-z material was investigated, and the x-ray transmission gratings with a line density of up to 6666 lines/mm were demonstrated. In the latter approach, which is suitable for low volume production, we investigated the x-ray mask pattern correction during the electron beam lithography process and the diffraction effect between the mask and wafer during the x-ray lithography process, and we demonstrated the precise control ability of line width and vertical side-wall profile. A large number of x-ray transmission gratings with a line density of 5000 lines/mm and Au absorber thickness of up to 580 nm were fabricated. The optical characterization results of the fabricated x-ray transmission gratings were given, suggesting that these two reliable approaches also promote the development of x-ray diffractive optical elements. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Structural characterization of the third polymorph of silicon nitride, synthesized under high-pressure and high-temperature conditions, has been obtained by Rietveld structure refinements of X-ray powder diffraction data recorded using synchrotron radiation. The material has a cubic spinel structure at 295 K with a space group Fd-3m, Z = 8, a unit cell of a = 7.7339 ± 0.0001 A, nitrogen position x = 0.2583 ± 0.0001, and density ρ = 3.75 ± 0.02 g cm−3. The complete structural data obtained should offer a firm basis for understanding the properties of the novel material. One example is present for the Raman spectroscopy data of the material.

A series of low-dose ( 12 ions cm −2 ) fullerene ion implantations in silicon has been carried out at 25°C over the energy range 100–530 keV. The resulting damage was measured quantitatively by Rutherford backscattering (RBS), using 2.0 MeV helium ions. This is an extension of an earlier study [J.B. Mitchell, J.A. Davies, L.M. Howe, R.S. Walker, K.B. Winterbon, G. Foti and J.A. Moore, Proc. 4th Intl. Conf. on Ion Implantation in Semiconductors, (Plenum Press, New York, 1975), p. 493.] of cluster-ion damage in Si where we had observed a 15-fold increase in damage-creation efficiency — i.e., the number of displaced Si atoms per keV of deposited energy — in going from (8.8 keV) monatomic carbon to (53 keV) C 6 + . Using the same 8.8 keV per carbon, we find that a 530 keV fullerene (C 60 + ) ion displaces 100 times more Si atoms than a 53 keV C 6 + ion; thus C 60 + exhibits an additional 10-fold increase in damage creation efficiency compared to C 6 + . At 100 keV, the deposited (nuclear) energy density θ within the central core of each C 60 + cascade (∼ 1.5 ev per Si atom) is considerably larger than the Si heat of melting. Not surprisingly, the observed number of displaced Si atoms also exceeds the theoretical cascade volume, thus providing strong evidence for some sort of spike effect. Despite the high damage levels involved, scanning tunneling microscopy revealed no evidence of any anomalous surface structures or craters. Comparison of the present C 60 + data with earlier Si implantation studies, where a variety of ions (C, Ga, As, Sb, Te, Bi) and energies (10–60 keV) had been used, confirms the previous suggestion that room temperature damage in Si is governed mainly by the cascade energy density θ (eV/atom).

Dilute bismides are a group of emerging materials with unique properties. Incorporation of a small amount of Bi in common III-V host materials results in large band-gap reduction and strong spin-orbit splitting, leading to potential applications in near-infrared (NIR) and mid-infrared (MIR) optoelectronics. Recent progresses on molecular beam epitaxy (MBE) of novel III-Sb-Bi, i.e. GaSbBi and InSbBi thin films from our group are summarised in this paper. Quantum well structures based on GaSbBi and InGaAsBi aiming for the optical communication window were grown and characterized.

Transmission gratings with a period of 100 nm for extreme ultraviolet interference lithography are fabricated with 2 groups of 50 nm thick Cr bars on a 100 nm thick Si3N4 film. The fabrication process starts with depositing Si3N4 on both sides of (100) Si wafers by LPCVD, followed by electron beam lithography of ZEP520A resist, evaporation of Cr and resist lift-off. A 120 nm thick stop layer of Au is then evaporated onto the surrounding area to eliminate unwanted transmission. Finally, a pair of Si3N4 windows are opened on the back side by dry etching, and the Si under the grating pattern is removed by KOH anisotropic wet etching. Diffraction measurement shows an acceptable first order efficiency of the gratings at the wavelength of 13.4 nm. Using the fabricated gratings at the interference lithography beam line of Shanghai Synchrotron Radiation Facility, economic and efficient fabrication of gratings with a doubled pitch, namely 50 nm period gratings, can be expected.

In this work we have measured lifetimes, oscillator strengths and hyperfine structures in Ho II. Accurate atomic structure data are of importance for element identification in steller atmospheres as well as in atomic structure studies. Lifetimes of 3 excited levels, all observed in stellar spectra, have been measured using electro-optic modulation spectroscopy in the ultraviolet. Oscillator strengths have furthermore been extracted by analyzing the time evolution of the laser excitation in the Rabi-regime. Previous to this study no lifetime and oscillator strength data were known in Ho II. In addition, the hyperfine structures of 3 low odd levels and 2 excited levels, has been accurately measured using fast beam laser spectroscopy. These data are analyzed using Multi-Configuration Dirac-Fock (MCDF) wavefunctions.

Ge nanostructures embedded in silica matrix are emerging as a promising material for new generation devices due to the unique electric and photonic properties. In this paper, Ge nanoclusters and nanocylinders with Ge shell were successfully formed by the high energy electron irradiation in the PECVD deposited glass. In addition, large area Ge nanoclusters were also created by heat-treatment of PECVD deposited glass film. These nanostructures were characterized in terms of size, composition, distribution and crystalline state by using TEM, HRTEM, EDS, SEM, Raman spectroscopy, and SIMS. Waveguides doped with Ge nanoclusters were fabricated and their absorption has been characterized in a wavelength range from 500nm to 1700nm.

Molecular beam epitaxy for GaSb1-xBix is investigated in this article. The growth window for incorporation of Bi in GaSb was found. Strategies of avoiding formation of Bi droplets and enhancing Bi incorporation were studied. The Bi incorporation was confirmed by SIMS and RBS measurements. The Bi concentration in the samples was found to increase with increasing growth temperature and Bi flux. The position of GaSb1-xBix layer peak in XRD rocking curves is found to be correlated to Bi composition. Surface and structural properties of the samples were also investigated. Samples grown on GaSb and GaAs substrates were compared and no apparent difference for Bi incorporation was found.

The storage ring ASTRID is built for studies in atomic physics, collision physics and laser physics. Beams have been laser cooled to temperature below 1 mK and beam dynamics studied by laser spectroscopy. The role of transverse excitations has been investigated and parameters determining onset of condensation studied. Rf‐laser double resonance spectroscopy has been performed and strict limits put on the requirements for coherent Ramsey‐spectroscopy.

Four high resolution negative electron beam resists are compared: TEBN-1 from Tokuyama Corp. Japan, ma-N 2401XP and mr-L 6000.1XP from microresist technology GmbH Germany, and SU-8 2000 series from MicroChem Corp., USA. Narrow linewidth high density patterns are defined by 100kV electron beam lithography, and the pattern is transferred into silicon by a highly anisotropic SF6∕O2∕CHF3 based reactive ion etch process with a selectivity between silicon and the investigated resists of approximately 2. 20nm half-pitch lines and 10nm lines with a pitch down to 60nm are written and transferred into silicon.

Thermal nanoimprint lithography (NIL) of the cyclic olefin copolymeric thermoplast Topas® is demonstrated. Topas® is highly UV-transparent, has low water absorption, and is chemically resistant to hydrolysis, acids and organic polar solvents which makes it suitable for lab-on-a-chip applications. In particular, Topas® is suitable for micro systems made for optical bio-detection since waveguides for UV-light can be made directly in Topas®. In this article full process sequences for spin coating Topas® onto 4 in. silicon wafers, NIL silicon stamp fabrication with micro and nanometer sized features, and the NIL process parameters are presented. The rheological properties of Topas® are measured and the zero shear rate viscosity is found to be 2.16×104 Pa s at 170 °C and 3.6×103 Pa s at 200 °C while the dominant relaxation time is found to be 4.4 s and 0.9 s, respectively. The etch resistance of Topas® to two different reactive ion etch processes, an oxygen plasma, and an anisotropic silicon etch, is found to ...

Publisher Summary This chapter presents an experimental test setup for the study of the dipole force in a fast atom beam. In contrast to the scattering force that saturates at high-intensity lasers, the dipole force requires the atomic transitions to be saturated to observe decelleration/acceleration for a blue/ red shifted detuning. In this way, a dipole force that is much larger than the scattering force can be realized. The condition for the dipole force to be optimum is that the velocity of the particles must be low relative to the standing wave. This can conveniently be satisfied in a transverse geometry in atomic beams; however, at sufficiently high Rabi frequencies, cooling is even observed in a longitudinal geometry. Fast beams, produced in ion sources and extracted by ion optics, have typical relative velocity spreads Δv/v ∼ 10–3 or better, corresponding to velocity spreads Δν ∼ 20 m/sec. This makes stimulated laser cooling an attractive possibility for cooling of fast beams, with cooling times limited by the transit time.

Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are studied. Strong In and Ga inter-diffusion induced by Bi incorporation is observed and discussed.

A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formation of Bi4Te3 while Bi2Te3 is formed at higher ratios. Transport measurements reveal that Bi2Te3 has higher electron mobility than Bi4Te3.