In Situ Microbeam Surface X-ray Scattering Reveals Alternating Step Kinetics During Crystal Growth

Local detection of X-ray spectroscopies with an in-situ AFM

The in situ combination of Scanning Probe Microscopies (SPM) with X-ray microbeams adds a variety of new possibilities to the panoply of synchrotron radiation techniques. In this paper we describe an optics-free AFM/STM that can be directly installed on synchrotron radiation end stations for such combined experiments. The instrument can be used just for AFM imaging of the investigated sample or can be used for detection of photoemitted electrons with a sharp STM-like tip, thus leading to the local measure of the X-ray absorption signal. Alternatively one can can measure the flux of photon impi…

An instrument for advanced in situ x-ray studies of metal-organic vapor phase epitaxy of III-nitrides

We describe an instrument that exploits the ongoing revolution in synchrotron sources, optics, and detectors to enable in situ studies of metal-organic vapor phase epitaxy (MOVPE) growth of III-nitride materials using coherent x-ray methods. The system includes high-resolution positioning of the sample and detector including full rotations, an x-ray transparent chamber wall for incident and diffracted beam access over a wide angular range, and minimal thermal sample motion, giving the sub-micron positional stability and reproducibility needed for coherent x-ray studies. The instrument enables …

A comparison of in- and ex situ generated shear bands in metallic glass by transmission electron microscopy

Shear bands originating from in situ tensile tests of Al$_{88}$Y$_{7}$Fe$_{5}$ melt-spun ribbons conducted in a transmission electron microscope are compared with ones which had formed ex situ during cold rolling. During in situ straining, the observations of a spearhead-like shear front, a meniscus-like foil thickness reduction and no apparent shear steps to accommodate strain suggest shear band initiation by a rejuvenating shear front followed by shearing along the already softened paths. This leads to necking and subsequent failure under the reduced constraint of a 2D geometry in the thin f…

Dynamics of Atomic Steps on GaN (0001) during Vapor Phase Epitaxy

Images of the morphology of GaN (0001) surfaces often show half-unit-cell-height steps separating a sequence of terraces having alternating large and small widths. This can be explained by the $αβαβ$ stacking sequence of the wurtzite crystal structure, which results in steps with alternating $A$ and $B$ edge structures for the lowest energy step azimuths, i.e. steps normal to $[0 1 \bar{1} 0]$ type directions. Predicted differences in the adatom attachment kinetics at $A$ and $B$ steps would lead to alternating $α$ and $β$ terrace widths. However, because of the difficulty of experimentally id…

单晶Ge在Sb离子注入过程中的无序与空腔演化：光谱椭偏原位监测

Disorder and cavity evolution in single-crystalline Ge during implantation of Sb ions monitored in-situ by spectroscopic ellipsometry

本研究利用原位光谱椭偏技术监测200-keV Sb离子注入单晶Ge过程中的损伤积累，发现约1E15 cm-2注量下发生完全非晶化与空腔形成，最终形成约200 nm改性层，并观察到准周期重组行为。

金纳米线受限生长过程中的各向异性应变变化

Anisotropic strain variations during the confined growth of Au nanowires

本研究利用多种原位X射线散射与光学反射技术，监测了阳极氧化铝模板中金纳米线的电化学生长过程，发现通过控制沉积时间可人为调节纳米结构的各向异性晶格应变，并观察到电迁移应力引起的晶格参数波动。