Transmission electron microscopical studies of the layered structure of the ternary semiconductor CuIn₅Se₈

The structure of the off-stoichiometric In-rich ternary phase CuIn5Se8 was studied by means of electron diffraction and high-resolution electron microscopy. The compound shows a layered structure with a 7-layer stacking sequence of closed-packed planes, which contains both cubic and hexagonal stacking of Se atoms. The studied CuIn5Se8 bulk crystal is known as the b-phase of this compound

CuAu-type ordering in epitaxial CuInS₂ films

Ordering of Cu and In atoms in near-stoichiometric CuInS2 epitaxial films grown on Si (111) by molecular beam epitaxy was studied by transmission electron microscopy. Nonchalcopyrite ordering of the metal atoms in CuInS2 is observed, which is identified as CuAu-type ordering. Sharp spots in electron diffraction patterns reveal the ordered Cu and In atom planes alternating along the [001] direction over a long range. High-resolution electron microscopy confirms this ordering. The CuAu-ordered structure coexists with the chalcopyrite ordered structure, in agreement with theoretical prediction

Line defects in epitaxial silicon films grown at 560 C

We present an investigation of line defects in epitaxially grown silicon layers using Secco defect etching and transmission electron microscopy TEM . 1 m thick layers were deposited onto Si 100 wafers at a substrate temperature of 560 C using electron cyclotron resonance chemical vapour deposition ECRCVD . Defect etching reveals a variety of etch pits related to extended defects. A detailed analysis of the orientations and shapes of etch pits related to line defects is carried out. Using this information it is then possible to assign different types of etch pits to line defects observed by TEM. The investigations show, that one type of defect are extended dislocations parallel to lt;112 gt;, while the direction of two other types are lt;110 gt; as well as lt;314 gt;, a direction uncommon for line defects in silico

XUV double-pulses with femtosecond to 650 ps separation from a multilayer-mirror-based split-and-delay unit at FLASH

Extreme ultraviolet (XUV) and X-ray free-electron lasers enable new scientific opportunities. Their ultra-intense coherent femtosecond pulses give unprecedented access to the structure of undepositable nanoscale objects and to transient states of highly excited matter. In order to probe the ultrafast complex light-induced dynamics on the relevant time scales, the multi-purpose end-station CAMP at the free-electron laser FLASH has been complemented by the novel multilayer-mirror-based split-and-delay unit DESC (DElay Stage for CAMP) for time-resolved experiments. XUV double-pulses with delays adjustable from zero femtoseconds up to 650 picoseconds are generated by reflecting under near-normal incidence, exceeding the time range accessible with existing XUV split-and-delay units. Procedures to establish temporal and spatial overlap of the two pulses in CAMP are presented, with emphasis on the optimization of the spatial overlap at long time-delays via time-dependent features, for example in ion spectra of atomic clusters

A study of carbon black Corax N330 with small angle scattering of neutrons and x rays

The carbon black Corax N330 called CB is used as a filler in elastomers. The properties of the surface are important for the binding of the elastomer to the carbon black. Porod s law requires the intensity to satisfy I q q 4. Rieker et al. observed an exponent of 3.7 for SAXS data, and concluded that the particle surface is fractally rough. Ruland critized this and suggested that the observed deviation is due to fluctuations of the spacing of the graphitic layer planes graphenes , which contribute a component q 2 to I q . Our SANS and SAXS data corrected for the fluctuation component revealed that the carbon black surface is essentially smoot

The epitaxial growth of sputtered silicon layers on differently oriented substrates at low temperature An electron microscopic study

The epitaxial growth of sputtered silicon layers on differently oriented substrates at low temperature An electron microscopic stud

Reconstruction of the mesoporous silica glass Gelsil 50

A stochastic optimization technique is applied to the construction of three dimensional models of Debye random media and random ensembles of mono disperse penetrable sphere