In situ analysis of catalyst composition during gold catalyzed GaAs nanowire growth

Abstract Semiconductor nanowires offer the opportunity to incorporate novel structures and functionality into electronic and optoelectronic devices. A clear understanding of the nanowire growth mechanism is essential for well-controlled growth of structures with desired properties, but the understanding is currently limited by a lack of empirical measurements of important parameters during growth, such as catalyst particle composition. However, this is difficult to accurately determine by investigating post-growth. We report direct in situ measurement of the catalyst composition during nanowire growth for the first time. We study Au-seeded GaAs nanowires inside an electron microscope as they grow and measure the catalyst composition using X-ray energy dispersive spectroscopy. The Ga content in the catalyst during growth increases with both temperature and Ga precursor flux.

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Post-nucleation evolution of the liquid-solid interface in nanowire growth

Nanotechnology ◽

10.1088/1361-6528/ac3e8d ◽

2021 ◽

Author(s):

Carina B Maliakkal ◽

Daniel Jacobsson ◽

Marcus Ulf Tornberg ◽

Kimberly Dick

Keyword(s):

Interface Energy ◽

Growth Direction ◽

Direction Selectivity ◽

Nanowire Growth ◽

Catalyst Droplet ◽

Transmission Electron ◽

Gaas Nanowires ◽

Amorphous Substrates ◽

First Time

Abstract We study using in situ transmission electron microscopy the birth of GaAs nanowires from liquid Au-Ga catalysts on amorphous substrates. Lattice-resolved observations of the starting stages of growth are reported here for the first time. It reveals how the initial nanostructure evolves into a nanowire growing in a zincblende <111> or the equivalent wurtzite <0001> direction. This growth direction(s) is what is typically observed in most III-V and II-VI nanowires. However, the reason for this preferential nanowire growth along this direction is still a dilemma. Based on the videos recorded shortly after the nucleation of nanowires, we argue that the lower catalyst droplet-nanowire interface energy of the {111} facet when zincblende (or the equivalent {0001} facet in wurtzite) is the reason for this direction selectivity in nanowires.

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Probing atomic positions of adsorbed ammonia molecules in zeolite

Chemical Communications ◽

10.1039/c5cc10476a ◽

2016 ◽

Vol 52 (16) ◽

pp. 3422-3425 ◽

Cited By ~ 19

Author(s):

Lin Ye ◽

Benedict T.W. Lo ◽

Jin Qu ◽

Ian Wilkinson ◽

Tim Hughes ◽

...

Keyword(s):

X Ray Diffraction ◽

Guest Molecules ◽

X Ray ◽

Adsorbed Ammonia ◽

Experimental Errors ◽

Zeolite P ◽

First Time ◽

Microporous Solids

The atomic positions and interactions between adsorbed guest molecules, such as ammonia in H-ZSM-5 microporous solids, are for the first time revealed by using in situ synchrotron powder X-ray diffraction combined with refinement within experimental errors.

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Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction

Journal of Synchrotron Radiation ◽

10.1107/s1600577517009584 ◽

2017 ◽

Vol 24 (5) ◽

pp. 981-990 ◽

Cited By ~ 6

Author(s):

Arman Davtyan ◽

Sebastian Lehmann ◽

Dominik Kriegner ◽

Reza R. Zamani ◽

Kimberly A. Dick ◽

...

Keyword(s):

Bragg Peak ◽

Stacking Faults ◽

Growth Direction ◽

X Ray Diffraction ◽

X Ray ◽

Patterson Function ◽

Transmission Electron ◽

Gaas Nanowires ◽

Gaas Nanowire

Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [000\bar{1}] direction in the vicinity of the wurtzite 00\bar{1}\bar{5} Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire.

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Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

Minerals ◽

10.3390/min10010038 ◽

2019 ◽

Vol 10 (1) ◽

pp. 38

Author(s):

Rafał Juroszek ◽

Biljana Krüger ◽

Irina Galuskina ◽

Hannes Krüger ◽

Martina Tribus ◽

...

Keyword(s):

Crystal Structure ◽

High Temperature ◽

Single Crystal ◽

Chemical Formula ◽

Crystal Chemical Formula ◽

Single Crystal Diffraction ◽

Bending Vibrations ◽

X Ray ◽

First Time

The crystal structure of bentorite, ideally Ca6Cr2(SO4)3(OH)12·26H2O, a Cr3+ analogue of ettringite, is for the first time investigated using X-ray single crystal diffraction. Bentorite crystals of suitable quality were found in the Arad Stone Quarry within the pyrometamorphic rock of the Hatrurim Complex (Mottled Zone). The preliminary semi-quantitative data on the bentorite composition obtained by SEM-EDS show that the average Cr/(Cr + Al) ratio of this sample is >0.8. Bentorite crystallizes in space group P31c, with a = b = 11.1927(5) Å, c =21.7121(10) Å, V = 2355.60(18) Å3, and Z = 2. The crystal structure is refined, including the hydrogen atom positions, to an agreement index R1 = 3.88%. The bentorite crystal chemical formula is Ca6(Cr1.613Al0.387)Σ2[(SO4)2.750(CO3)0.499]Σ3.249(OH)11.502·~25.75H2O. The Raman spectra of bentorite from two different localities exhibit the presence of the main stretching and bending vibrations related to the sulfate group at 983 cm−1 (ν1), 1109 cm−1 (ν3), 442 cm−1 (ν2), and 601 cm−1 (ν4). Moreover, the presence of bands assigned to the symmetric Cr(OH)63− stretching mode and hydroxyl deformation vibrations of Cr–OH units at ~540 cm−1 and ~757 cm−1, respectively, may be used to distinguish between ettringite and bentorite. In situ high temperature single crystal XRD experiments show that the decomposition of bentorite starts at ca. 45 °C and that a dehydroxylation product similar to metaettringite is formed.

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Oxygen-Induced Reversible Structural Change of Supported fine Silver Particles Observed by In Situ Optical Absorption and X-ray Diffraction

MRS Proceedings ◽

10.1557/proc-195-31 ◽

1990 ◽

Vol 195 ◽

Author(s):

Akihisa Yanase ◽

Hiroshi Komiyama ◽

Kazunobu Tanaka

Keyword(s):

Optical Absorption ◽

Surface Stress ◽

Lattice Parameter ◽

Silver Particles ◽

X Ray Diffraction ◽

X Ray ◽

Ambient Gases ◽

First Time ◽

Shape Of Particles

ABSTRACTIn situ measurements of optical absorption and x-ray diffraction for small supported silver particles were performed under defined atmospheres at temperatures below 723 K. We found, for the first time, reversible changes both in optical absorption spectrum and lattice parameter of silver particles against the cyclic exchange of ambient gases between 5% H2/He and 1% 02/He. The present data indicate that the adsorption of oxygen results in a reduction in surface stress of silver particles, leading to a change in the shape of particles.

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Formation of hydroxysulphate and hydroxycarbonate green rusts in the presence of zinc using time-resolved in situ small and wide angle X-ray scattering

Mineralogical Magazine ◽

10.1180/minmag.2008.072.1.159 ◽

2008 ◽

Vol 72 (1) ◽

pp. 159-162 ◽

Cited By ~ 11

Author(s):

I. A. M. Ahmed ◽

S. Shaw ◽

L. G. Benning

Keyword(s):

Unit Cell ◽

Wide Angle ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Ph Dependent ◽

Green Rusts ◽

First Time ◽

Ray Scattering

AbstractThe formation and transformation of hydroxysulphate (GRSO4) and hydroxycarbonate (GRCO3) Green Rusts were studied in situ using synchrotron-based time-resolved small and wide angle X-ray scattering. The time-resolved data revealed, for the first time, the pH dependent transition from poorly-ordered schwertmannite (pH <6.5) into GRSO4 (pH ~6.8) followed by GRCO3 (at pH ~9.6). These data also showed that the addition of Zn to the starting sulphate Fe2+/Fe3+ solution resulted in a change in size of the GR unit-cell due to substitution of Zn into the GR structure.

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In Situ Soldering Process Technique by Synchrotron X-Ray Imaging

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.754-755.508 ◽

2015 ◽

Vol 754-755 ◽

pp. 508-512

Author(s):

M.A.A. Mohd Salleh ◽

A. Sugiyama ◽

Hideyuki Yasuda ◽

Stuart D. McDonald ◽

Kazuhiro Nogita

Keyword(s):

Real Time ◽

Void Formation ◽

In Situ Observation ◽

Cu Substrate ◽

X Ray ◽

Soldering Process ◽

X Ray Imaging ◽

Free Solder ◽

First Time

This paper demonstrates the development of an experimental technique of in-situ observation for soldering of Sn-0.7wt%Cu lead-free solder on a Cu substrate which was achieved for the first time by synchrotron X-ray imaging. Reactions between liquid solder and Cu substrate during a soldering process were able to be recorded in real-time. Individual stages of the soldering process consisted of flux activation in removal of Cu oxide, solder melting and contact with the Cu substrate (wetting) and intermetallic compound (IMC) and void formation between the solder and Cu substrate. The technique development which includes experimental setup with calculated optimum beam energy in the range of 20 – 30 keV appears to result in a clear observation of real-time X-ray imaging of the soldering process. This technique provides a key method to understand the mechanism of formation of micro-electronic inter-connects for future electronic packaging applications.

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In-situ High Temperature X-ray Diffraction Study of the Am-O System

MRS Advances ◽

10.1557/adv.2017.200 ◽

2016 ◽

Vol 1 (62) ◽

pp. 4133-4137 ◽

Cited By ~ 1

Author(s):

E. Epifano ◽

R. C. Belin ◽

J-C Richaud ◽

R. Vauchy ◽

M. Strach ◽

...

Keyword(s):

High Temperature ◽

Lattice Parameter ◽

Minor Actinide ◽

Controlled Atmosphere ◽

X Ray Diffraction ◽

X Ray ◽

Binary Phase Diagrams ◽

First Time ◽

O Phase

ABSTRACTIn the frame of minor actinide recycling, (U,Am)O2 are promising transmutation targets. To assess the thermodynamic properties of the U-Am-O system, it is essential to have a thorough knowledge of the binary phase diagrams, which is difficult due to the lack of thermodynamic data on the Am-O system. Nevertheless, an Am-O phase diagram modelling has been recently proposed by Gotcu. Here, we show a recent investigation of the Am-O system using in-situ High Temperature X-ray Diffraction under controlled atmosphere. By coupling our experimental results with the thermodynamic calculations based on the Gotcu model, we propose for the first time a relation between the lattice parameter and the departure from stoichiometry.

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Optical far-field extinction of a single GaAs nanowire towards in situ size control of aerotaxy nanowire growth

Nanotechnology ◽

10.1088/1361-6528/ab5fe4 ◽

2020 ◽

Vol 31 (13) ◽

pp. 134001 ◽

Cited By ~ 1

Author(s):

Yang Chen ◽

Nicklas Anttu ◽

Sudhakar Sivakumar ◽

Eleni Gompou ◽

Martin H Magnusson

Keyword(s):

Size Control ◽

Nanowire Growth ◽

Far Field ◽

Gaas Nanowire

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RF-Magnetron Sputtered Strontium Titanate: Structure, Processing and Property Relationships

MRS Proceedings ◽

10.1557/proc-603-57 ◽

1999 ◽

Vol 603 ◽

Cited By ~ 2

Author(s):

B.J. Gibbons ◽

Y. Fan ◽

A.T. Findikoglu ◽

D.W. Reagor ◽

Q.X. Jia

Keyword(s):

Room Temperature ◽

Low Frequency ◽

Ozone Treatment ◽

X Ray Diffraction ◽

X Ray ◽

Treated Sample ◽

Diffraction Peaks ◽

Compositional Variations ◽

First Time

AbstractThe low frequency dielectric properties of epitaxial SrTiO3 thin films deposited on LaAlO3 are presented. The films were deposited using radio-frequency magnetron sputtering from stoichiometric targets in an Ar/O2 atmosphere. For the first time, the effects of in situ ozone annealing during the early stages of deposition were explored. X-ray diffraction results indicated that the ozone treatment resulted in more symmetric and sharper diffraction peaks (2 Θ- FWHM decreased from 0.17° to 0.10°). In addition, the peaks for the ozone treated samples were shifted in 2 Θ towards values approaching the bulk value. Rutherford backscattering measurements showed Sr/Ti ratios of 1:1 for these samples, indicating these peak shifts are not due to compositional variations. The dielectric constant of the ozone treated samples increased from 275 at room temperature to 1175 at 22 K (measured at 100 kHz). The effective loss tangent of the device remained between 1 × 10−4 and 1 × 10−3 down to 100 K, where it began to increase. The tunability was also measured. The ozone treated sample showed tunability of 46%, 43% and 38% at 22 K, 40 K and 60 K, respectively. Finally, similar measurements were completed at 1 MHz, indicating a minimal dependence of these properties on frequencies in this range.

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