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Phase pure Na-β''-alumina ceramics are excellent electrolytes for molten-salt and all-solid-state batteries. However, controlled processing of this complex material is required to obtain the desired phase content, as Na-β''-alumina can accommodate variable amounts of sodium within its conduction slab. On the one hand, addition of dopant ions (e.g. Li+, Mg2+) influences stability and sodium content of Na-β''-alumina. On the other hand, β''-aluminas are prone to sodium evaporation, resulting in compositional changes during high-temperature sintering. Here, we show that while sodium evaporation indeed becomes significant at temperatures > 1300 °C, Na-β''-alumina ceramics of constant total composition can be prepared at strongly variable sintering conditions by applying an encapsulation. Nevertheless, our study reveals that the sodium content in the Na-β''-alumina crystal structure varies with the processing temperature. This is indicated by changes in the c-lattice parameter, which decreases with increasing sintering temperature, corresponding to an increase in sodium content.

The dislocation structure of single-crystalline germanium crystals grown by the Czochralski method in [2 1 1] and [1 1 0] directions has been examined by white beam X-ray topography. The dislocation densities in different parts of the crystals ranged from around 40 to 4000 cm−2. It was demonstrated that utilizing a well-executed Dash necking procedure with high growth speeds in growth directions parallel to a dislocation glide plane leads to the selection of dislocation line and type. Dislocations in the [2 1 1] crystal were mainly oriented in the [1 0 1] and [1 1 0] directions and hence confined within the ( 1 1) glide plane. A comprehensive Burgers vector analysis revealed that they were predominantly screw dislocations. The dislocation lines in the [1 1 0] crystal were mostly aligned to the [0 1 ], [1 0 ], and [1 0 1] orientations, within the ( 1 1) and (11) glide planes and predominantly 60° dislocations.

A germanium crystal of high purity was grown in H2 with a maximum dislocation density of 3000 cm−2, which was estimated by white beam x-ray topography. Due to a dynamical diffraction effect, the topographs revealed the existence of vacancy clusters in the form of voids in dislocation-free parts of the crystal. Etch pit density analysis, the standard technique employed for crystalline wafers to determine dislocation density, failed to reliably represent dislocations in dislocation-free parts of the crystal. On the other hand, we were able to identify a different type of etching pattern for a dislocation-free crystal. Microwave photoconductance decay was utilized to determine the charge carrier lifetime, which was found to be up to 500 μs for regions with dislocations, while being only 100 μs for dislocation-free parts of the crystal.

Bent crystals can be used to deflect high-energy charged particles for beam extraction and/or beam collimation at accelerator facilities, thanks to the channelling phenomenon. In the present paper, two perfect silicon mono-crystals were bent using two different methods: sandblasting and the application of a carbon fibre composite. In particular, these samples were obtained for the realization of bent crystal prototypes to be used to steer the 7 TeV proton beam of the Large Hadron Collider in the context of the CRYSBEAM project. The two bending methods were selected since they allow a very homogeneous curvature of the crystals to be obtained, which is essential for high channelling efficiency. Moreover, the deformation obtained is self-standing, i.e. there is no need for any external device to keep the samples bent. Self-standing curvature can be useful because the presence of an external bender could be a severe limitation in the collider beam-pipe. The curvature of the samples was measured through high-energy X-ray diffraction at the ID11 beamline of the European Synchrotron Radiation Facility in Grenoble, France. Since the diffraction efficiencies obtained were in good agreement with theoretical expectations, it follows that the manufacturing techniques did not damage the samples, i.e. the crystallographic quality was preserved. Finally, the crystal quality of the sandblasted sample was investigated in detail at the synchrotron source at Karlsruhe Institute of Technology by X-ray white-beam topography. The measurements showed no diffusion of defects from the machined surfaces to the crystal bulk.

The review on bulk growth of SiC includes a basic overview on the widely used physical vapor transport method for processing of 4H-SiC boules as well as the discussion of three current research topics: (a) Sublimation bulk growth of large area, freestanding cubic SiC, (b) in-situ Visualization of the PVT Process using 2D and 3D X-ray based imaging and (c) prediction of dislocation formation and motion in SiC using a continuum model of dislocation dynamics (CDD).

Screw-type dislocations like micropipes (MP) and threading screw dislocations (TSD) are prohibiting the function or at least diminishing the efficiency of electronic devices based on silicon carbide (SiC). Therefore, it is essential to characterize wafers in an efficient and fast manner. Molten potassium hydroxide (KOH) etching or white-beam X-ray topography (SWXRT) are either destructive or not economically viable for an in-depth characterization of every wafer of one SiC crystal. Birefringence microscopy is being utilized as a fast and non-destructive characterization method. Instead of microscopic setups, commercially available flat-bed scanners equipped with crossed polarizer foils can be used for fast large-area scans. This work investigates the feasibility of such a setup regarding the detection rate of MPs and TSDs. The results of a full-wafer mapping are compared with birefringence microscopy and KOH etching. In the investigated sample clusters of MPs caused by a polytype switch in the beginning of the growth could be identified by both birefringence microscopy and the flat-bed scanner setup, as well as small angle grain boundaries and TED arrays. However, the resolution of the scanner was not sufficient to identify TSDs. Nevertheless the setup proves to be an easy-to-setup and cheap characterization method, able to quickly identify defect clusters in 4H-SiC wafers.

This article describes complete characterization of the polygonal dislocation half-loops (PDHLs) introduced by scratching and subsequent bending of an Si(111) crystal. The study is based on the X-ray topo-tomography technique using both a conventional laboratory setup and the high-resolution X-ray image-detecting systems at the synchrotron facilities at KIT (Germany) and ESRF (France). Numerical analysis of PDHL images is performed using the Takagi–Taupin equations and the simultaneous algebraic reconstruction technique (SART) tomographic algorithm.

X-ray diffraction imaging (XRDI) (topography) measurements of silicon die warpage within fully packaged commercial quad-flat no-lead devices are described. Using synchrotron radiation, it has been shown that the tilt of the lattice planes in the Analog Devices AD9253 die initially falls, but after 100 °C, it rises again. The twist across the die wafer falls linearly with an increase in temperature. At 200 °C, the tilt varies approximately linearly with position, that is, displacement varies quadratically along the die. The warpage is approximately reversible on cooling, suggesting that it has a simple paraboloidal form prior to encapsulation; the complex tilt and twisting result from the polymer setting process. Feasibility studies are reported, which demonstrate that a divergent beam and quasimonochromatic radiation from a sealed X-ray tube can be used to perform warpage measurements by XRDI in the laboratory. Existing tools have limitations because of the geometry of the X-ray optics, resulting in applicability only to simple warpage structures. The necessary modifications required for use in situations of complex warpage, for example, in multiple die interconnected packages are specified. © The Author(s), 2021. Published by Cambridge University Press on behalf of International Centre for Diffraction Data. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. [doi:10.1017/S088571562100021X]

Due to the functional limitations of SiO2 for SOI applications, alternative dielectric materials have been investigated. Alternative SOI materials in this work include, AlN and AlGaN. The dielectrics were deposited using MOCVD, and with the aid of PECVD deposited SiO2, and the SiO2 was directly bonded to a handle Si wafer. Tensile tests were performed on the samples to examine the fracture behavior and maximum tensile stresses, with results being comparable to a traditional SOI. Characterization was undertaken using TEM to understand the microstructural and interfacial properties of alternative SOI. High crystal quality Al(Ga)N was achieved on a Si(111) substrate that generally contained well defined chemical interfaces. Finally, synchrotron X-ray diffraction topography was used to understand the topographical strain profile of the device and handle wafers. Topography results showed different strain network properties between the device and handle wafer. This work has demonstrated preliminary feasibility of using alternative dielectrics for SOI applications.

White beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection., White-beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. The voids are visible because of a dynamical diffraction contrast. It is shown that voids occur only in dislocation-free parts of the crystal and do not show up in regions with homogeneous and moderate dislocation density. It is further suggested that the voids originate from clustering of vacancies during the growth process. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection.

During 4H silicon carbide (4H-SiC) homoepitaxy and post-growth processes, the development of stress relaxation has been observed, in which interfacial dislocations (IDs) are formed at the epilayer/substrate interface, relaxing the misfit strain induced by the nitrogen doping concentration difference between the epilayer and substrate. It is widely believed that an interfacial dislocation is created by the glide of a mobile segment of a basal plane dislocation (BPD) in the substrate or epilayer towards the interface, leaving a trailing edge component right at the interface. However, direct observation of such mechanisms has not been made in SiC before. In this work, we present an in situ study of the stress relaxation process, in which a specimen cut from a commercial 4H-SiC homoepitaxial wafer undergoes the stress relaxation process during a high-temperature heat treatment while sequential synchrotron white beam X-ray topographs were recorded simultaneously. Based on the dynamic observation of this process, it can be concluded that thermal stress plays a role in the relaxation process while the increased misfit strain at elevated temperature most likely drives the formation of an interfacial dislocation.

We present in-situ observations of the dynamical operation of multiple double-ended Frank-Read dislocation sources in a PVT-grown 4H-SiC wafer under thermal gradient stresses. The nucleation of these sources is facilitated by a specific configuration consisting of one basal plane dislocation (BPD) segment pinned by two threading edge dislocations (TEDs). This configuration is formed during PVT crystal growth by deflection of TEDs on to the basal planes by macrosteps and re-deflection of resulting BPDs back into TEDs. Under the influence of thermal gradient stresses induced by heating inside a double ellipsoidal mirror furnace, the pinned BPD segment glides and activates dislocation multiplication by the double Frank-Read source mechanism. A more intricate mechanism of swapping of TED pinning points between Frank-Read sources lying on same basal plane is identified, enabling one dislocation loop to effectively “pass through” the other dislocations on same basal plane.

This study investigates the effect on crystal growth and physical properties of triglycine sulfate (TGS) single crystals grown in the presence of surfactants, namely the anionic surfactants sodium dodecyl sulfate (SDS) and sodium 1-decanesulfonate (S1-DS). Pure TGS as well as SDS_TGS and S1-DS_TGS single crystals have been grown from aqueous solution, using a temperature lowering technique. The use of surfactants affects both crystal growth rate and shape. Concerning the latter feature, SDS_TGS crystals show larger (0 1 0) faces (b-face) and the S1-DS_TGS crystals show an elongation in [0 1 0] direction (b-direction). All samples are monoclinic and show the same Curie temperature (49 °C) as pure TGS. The UV–Vis transmittance of the crystals is found to be decreased due to the presence of surfactants during the growth process. At room temperature, the relative permittivity of the samples is decreased from 10.5 for pure TGS to 7.5 and 5.5 for SDS_TGS and S1-DS_TGS crystals, respectively. However, all crystals show the same pyroelectric coefficient of 168 μC/(m2·K) at room temperature. With that, the pyroelectric voltage figure of merit (FOM) (pc/ (e.e0)) is increased from 201 kV/(m·K) for pure TGS up to 245 kV/(m·K) for SDS_TGS, and up to 317 kV/(m·K) for S1-DS_TGS. The energy harvesting figure of merit ( p c 2 / e  · e 0 ) is increased from 30.37 J/(m3.K2) for pure TGS to 42.52 and 58 J/(m3.K2) for SDS_TGS and S1-DS_TGS crystals, respectively.

The temperature-dependent components of the anisotropic thermal diffusivity of lead iodide (PbI 2 ) have been measured by Laser Flash Analysis (LFA). The temperature range used was −100 °C to +350 °C. The temperature-dependent specific heat capacity c p was determined independently by Differential Scanning Calorimetry (DSC) to calculate the thermal conductivities for PbI 2 from the thermal diffusivity data. At 27 °C, the thermal conductivity in the c-axis-direction, k 33 , is 0.315 W m −1 K −1 , whereas the component perpendicular to the c-axis, k 11 , is 0.681 W m −1 K −1 . The anisotropy ratio k 33 / k 11 changes from 1:2 at −100 °C to 1:2.4 at +350 °C. The temperature dependencies of both k 33 and k 11 in this range can be very well fitted with 3rd order polynomials.

Meteoritics & planetary science 52(7), 1465 - 1474 (2017). doi:10.1111/maps.12840, –Hypervelocity collisions of solid bodies occur frequently in the solar syst em andaffect rocks by shock waves and dynamic loading. A range of shock metamorphic effectsand high-pressure polymorphs in rock-forming minerals are known from meteorites andterrestrial impact craters. Here, we investigate the formation of high-pressure polymorphs ofa-quartz under dynamic and nonhydrostatic conditions and compare these disequilibriumstates with those predicted by phase diagrams derived from static experiments underequilibrium conditions. We create highly dynamic condition s utilizing a mDAC and studythe phase trans formations in a-quartz in situ by synchrotron powder X-ray diffraction.Phase transitions of a-quartz are studied at pressures up to 66.1 and different loading rates.At compression rates between 0.14 and 1.96 GPa s$^{-1}$, experiments reveal that a-quartz isamorphized and partially converted to stishovite between 20.7 GPa and 28.0 GPa.Therefore, coesite is not formed as would be expected from equilibrium conditions. Withthe increasing compression rate, a slight increa se in the transition pressure occurs. Theexperiments show that dynamic compression causes an instantaneous formation ofstructures consisting only of SiO$_6$ octahedra rather than the rearrangement of the SiO$_4$ tetrahedra to form a co esite. Alt hough shock compression rates are orders of magnitudefaster, a similar mechanism could operate in impact events., Published by Wiley, Hoboken, NJ

We describe an X-ray diffraction imaging technique for nondestructive, in situ measurement of die warpage in encapsulated chip packages at acquisition speeds approaching real time. The results were validated on a series of samples with known inbuilt convex die warpage, and the measurement of wafer bow was compared with the results obtained by optical profilometry. We use the technique to demonstrate the impact of elevated temperature on a commercially sourced micro quad flat nonlead chip package and show that the strain becomes locked in at a temperature between 94 °C and 120 °C. Using synchrotron radiation at the Diamond Light Source, warpage maps for the entire $2.2~\textrm {mm} \times 2.4~\textrm {mm} \times 150$ - $\mu \text{m}$ Si die were acquired in 50 s, and individual line scans in times as short as 500 ms.

We report on the growth and characterization of several sapphire single crystals for the purpose of x-ray optics applications. Structural defects were studied by means of laboratory double-crystal X-ray diffractometry and white beam synchrotron-radiation topography. The investigations confirmed that the main defect types are dislocations. The best quality crystal was grown using the Kyropoulos technique with a dislocation density of 102-103 cm-2 and a small area with approximately 2*2 mm2 did not show dislocation contrast in many reflections and has suitable quality for application as a backscattering monochromator. As a result, a clear correlation between growth rate and dislocation density is observed, though growth rate is not the only parameter impacting the quality.

Large-area back-reflection and transmission X-ray diffraction topographs of bonded silicon-on-insulator (SOI) wafers made with synchrotron radiation allowed direct and simultaneous imaging of bonding-induced strain patterns of both the 7 μm thick (011) top layers and the (001) Si substrates of the SOI structures. The bonding-induced strain pattern consists of cells having a diameter of about 40 μm. Section topographs show a lattice misorientation of the adjacent cells of about 0.001° and the maximum observed strain-induced lattice plane rotation ten times larger, i.e. about 0.01°. Topographs made after etching away the insulator layer show no indication of residual strain or defects either in the silicon-on-insulator layer or in the substrate. This is in agreement with the experimentally determined maximum bonding stress of 30 MPa, which is much smaller than the estimated stress needed to nucleate dislocations.

Ammonothermally grown GaN is a promising substrate for high-power optoelectronics and electronics thanks to its scalability and high structural perfection. Despite extensive research, ammonothermal GaN still suffers from significant concentrations of impurities. This article discusses the evolution of impurity incorporation during growth of basic ammonothermal GaN, in specific whether the impurity concentration changes temporally along the growth direction and how the autoclave influences the impurity concentration. The effect of the impurities on the structural, electrical and optical properties of the grown crystal is also discussed. The chemical analysis is carried out by time of flight secondary ion mass spectroscopy (ToF-SIMS) and laser-ablation inductively-coupled plasma mass spectroscopy (LA-ICP-MS). Strain and dislocation generation caused by impurity concentration gradients and steps are studied by synchrotron radiation x-ray topography (SR-XRT). Fourier transform infrared (FTIR) reflectivity is used to determine the effect of the impurities on the free carrier concentration, and the luminescent properties are studied by low temperature photoluminescence (PL). The influence of the autoclave is studied by growing a single boule in multiple steps in several autoclaves. LA-ICP-MS and ToF-SIMS ion intensities indicate that the impurity concentrations of several species vary between different autoclaves by over an order of magnitude. SR-XRT measurements reveal strain at the growth interfaces due to impurity concentration gradients and steps. Oxygen is determined to be the most abundant impurity species, resulting in a high free carrier concentration, as determined by FTIR. The large variation in Mn concentration dramatically affects PL intensity.

Transmission X-ray diffraction imaging in both monochromatic and white beam section mode has been used to measure quantitatively the displacement and warpage stress in encapsulated silicon devices. The displacement dependence with position on the die was found to agree well with that predicted from a simple model of warpage stress. For uQFN microcontrollers, glued only at the corners, the measured misorientation contours are consistent with those predicted using finite element analysis. The absolute displacement, measured along a line through the die centre, was comparable to that reported independently by high-resolution X-ray diffraction and optical interferometry of similar samples. It is demonstrated that the precision is greater than the spread of values found in randomly selected batches of commercial devices, making the techniques viable for industrial inspection purposes.

Graphical abstractDisplay Omitted We outline the development of a novel laboratory-based X-ray diffraction methodology.First available lab-based technique for measuring stress/strain inside packaged chip.The technique is demonstrated at 25?C and processed at elevated temperatures up to 115?C.It has been proven through characterising commercially available packaged chips.Large thermal stresses are developed due mainly to die attach process. Reliability issues as a consequence of thermal/mechanical stresses created during packaging processes have been the main obstacle towards the realisation of high volume 3D Integrated Circuit (IC) integration technology for future microelectronics. However, there is no compelling laboratory-based metrology that can non-destructively measure or image stress/strain or warpage inside packaged chips, System-on-Chip (SoC) or System-in-Package (SiP), which is identified as a requirement by the International Technology Roadmap for Semiconductors (ITRS). In the work presented here, a triple-axis Jordan Valley Bede D1 X-ray diffractometer is used to develop a novel lab-based technique called X-ray diffraction 3-dimensional surface modelling (XRD/3DSM) for non-destructive analysis of manufacturing process-induced stress/warpage inside completely encapsulated packaged chips. The technique is demonstrated at room temperature and at elevated temperatures up to 115?C by in situ XRD annealing experiments. The feasibility of this technique is confirmed through the characterisation of die stress inside encapsulated commercially available ultra-thin Quad Flat Non-lead (QFN) packages, as well as die stress in embedded QFN packages at various stages of the chip manufacturing process.

We have developed a procedure to grow lead iodide (PbI 2 , 2H type) crystals using the Czochralski method applying an Ar counter pressure inside a fused silica chamber. The resulting crystal has a length of 3 cm and is free of cracks. Electron backscatter diffraction (EBSD) measurements demonstrate that the crystal grew along [1 1 2¯ 0] direction ( c -axis perpendicular to growth direction), which was defined by the PbI 2 seed. This means that a better control of the growth direction is possible using the Czochralski method. The EBSD patterns suggest a simplified preparation method of the very soft crystals using samples with a surface orientation perpendicular to (0 0 0 1). Rocking curves measured by high resolution X-ray diffraction (HRXRD) indicate that the structural quality of the approximately 80% single crystalline material is comparable to Bridgman–Stockbarger-grown crystals.

White beam X-ray diffraction imaging (topography) with an optimised CCD-detector system is used to monitor in-situ and in real time the nucleation, growth and movement of dislocations in silicon at high temperatures. It can be shown, that damage like microcracks and the surrounding strain fields in a wafer act as sources for dislocation loops, which end in slip bands far away from the source. The dislocations are arranged in channels of parallel {1 1 1} glide planes, which become visible as bands of parallel surface steps when the dislocations slip out on the back or front sides of the wafer. The width of such a channel or band depend on the dimensions of the damaged volume where the dislocations nucleate. This can be explained with a simple geometrical model.

A comprehensive study on the etching behaviour of threading dislocations in n-type substrates and n- and p-type homoepitaxial layers was performed. Defect selective etching (DSE) in molten KOH was applied to a large number of substrates and homoepitaxial layers covering the maximum available doping range in order to identify etching regimes and the influence of doping on the etch pattern. The types of threading dislocations present in n-type 4H–SiC substrates and n- and p-type homoepitaxial layers were investigated by synchrotron X-ray topography (SXRT). Based on the visibility criterion g → ⋅ b → = 0 , two types of threading dislocations, named TED II and TED III, were identified and reported for the first time. For a representative sample of each etching regime, the dislocation pattern obtained by SXRT was compared to the etch pattern to verify the etching method especially with respect to the interpretation of etch pits based on their shape and size: (1) a 1:1 correlation of etch pit and dislocation was found for all investigated samples and all doping levels. The etch pit density (EPD) on Si-face coincides with the dislocation density (DD) at the sample surface. (2) The sample’s doping state has to be taken into account for the determination of respective densities of different dislocation types like threading edge (TED) or threading screw (TSD) dislocations and micropipes. (3) In case of highly doped n-type substrates the results show that it is not possible to distinguish all dislocation types by the size and shape of their etch pits, regardless of etching parameters. (4) In case of p-type and low n-type samples TSDs can be distinguished from all types of TEDs by the size of their etch pits. (5) An additional etch pit type is observed in n-type samples with a doping level in the range of 2×10 16 –1×10 18 cm −3 . This additional etch pit type correlates to TED II dislocations due to our results.

Lead iodide (PbI2) crystals were synthesized with stoichiometric composition and with an excess of iodine or lead. Crystals were further doped by Ag, Au, Ge, and a number of rare-earth elements (RE). The structure of the crystals was analyzed by high resolution X-ray diffractometry (HRXRD) and electron backscatter diffraction (EBSD). The rocking curves measured by HRXRD confirm the crystal quality and EBSD measurements present the progress of sample preparation. Crystals have further been investigated by measuring electrical resistivity, low temperature photoluminescence, and optical transmission. Stoichiometric composition or that with low excess of lead has been shown to give best quality crystals. Doping with Ag leads to considerable decrease of electrical resistivity and at the same time gives optical gap as high as that of undoped samples. Doping with RE generally leads to the decrease of optical gap due to band tailing induced by lattice distortions. Low level RE doping in same cases (Ho, Tm) leads to pronounced gettering, thus giving high electrical resistivity and narrow PL bands.

The behaviour of dislocations in GaSb crystals grown in space both from a stoichiometric melt (floating zone method, FZ) and a Bi solution (floating solution zone, FSZ) respectively, is studied. Predominantly straight 60° dislocations with Burgers vectors of the type b = a/2 in (111) glide planes are identified. In the 20 mm long FZ single crystal the linear growing out of the dislocations is observed which reduces the dislocation density in the centre of the crystal to values below 300 cm–2. The Bi incorporation in the FSZ crystal results in a misfit between seed and grown crystal and in a network of misfit dislocations at the interface. Thermocapillary convection during growth as well as the surface tension may be the reasons for the presence of curved dislocations and the higher dislocation density within a 1 – 2 mm border region at the edges of both of the crystals. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Lead iodide (PbI2) shows excellent electronic properties for detection of ionizing radiation. We report the introduction of rare-earth elements and other elements as admixtures during synthesis to study their influence on the quality of single crystals. Synthesized material as well as single crystals have been characterized by measurements of electrical resistivity and low-temperature photo luminescence and index of refraction. The structural quality with respect to polytypes was analysed by electron back scatter diffraction. Makyoh topography was applied for surface studies.

The TopoTomo bending magnet beamline at the ANKA synchrotron facility in Karlsruhe (Germany) operates in the hard X-ray regime (above 6 keV). Recently, an X-ray micro-imaging station has been installed at TopoTomo. For typical imaging applications, a filtered white beam or from 2009 on a double-multilayer monochromator is used. In order to optimize the field of view and the resolution of the available indirect pixel detectors, different optical systems have been installed, adapted, respectively, to a large field of view (macroscope) and to high spatial resolution (microscope). They can be combined with different camera systems, ranging from 14-bit dynamic range CCDs to fast CMOS cameras. The spatial resolution can be brought substantially beyond the micrometer limit by using a Bragg magnifier. Due to the moderate flux of the beamline compared to insertion-device beamlines on third generation light sources, special emphasis has been put on the efficiency of the detectors via a dedicated scintillator concept. The layout of the beamline optics makes optimal use of the coherence properties. Thus, absorption contrast, phase-contrast and analyzer-based imaging can be applied. Additionally, white beam synchrotron topography is performed, using digital indirect X-ray pixel detectors as well as X-ray film.

Lead iodide PbI2 is an excellent and interesting candidate for high efficiency room temperature detectors working in the medium energy range of 1 keV–1 MeV. It can be widely applied in medicine, monitoring ecology, nondestructive defectoscopy and X-ray and gamma spectroscopy. The peculiarities of this material are high resistivity, ability to work in a wide range of temperatures and high chemical stability. The method of preparation was direct synthesis from lead and iodine. The material was further purified by zone melting and grown by Bridgman-Stockbarger method. In this work we have concentrated on the study of the influence of dopants such as lanthanides (Er,Gd, Ho, Tb, Tm, Yb, GdI3, HoI3, GdI3) and elements of other groups, such as Au, Ag, Ge on the physical, electrical and optical properties of the PbI2. These were evaluated by resistivity and low temperature photoluminescence measurements. The Synchrotron X-ray topography was successfully introduced to study defects. The quality of the material was analyzed after synthesis, zone melting and growth. The dependence on the concentration of dopants was investigated too.

Phase diagram analyses and crystal growth experiments of the novel ferroelectric tetragonal tungsten bronzes Ca x Ba 1 - x Nb 2 O 6 (calcium barium niobate, CBN) and Ca x Sr y Ba 1 - x - y Nb 2 O 6 (calcium strontium barium niobate, CSBN) were performed in this study. The quasi-binary phase diagram BaNb 2 O 6 – CaNb 2 O 6 was found to be similar to the related system BaNb 2 O 6 – SrNb 2 O 6 , but with a remarkably reduced existence region. In the quasi-ternary phase diagram CaNb 2 O 6 – SrNb 2 O 6 – BaNb 2 O 6 the stability field of Ca x Sr y Ba 1 - x - y Nb 2 O 6 mixed crystals was determined by X-ray powder diffraction of sintered and annealed samples. Large, transparent, and nearly colorless CBN and CSBN single crystals of high quality were grown by the Czochralski method. The dislocation network structure of the core region in the as-grown crystals was analyzed by X-ray topography employing white beam synchrotron radiation. Precise measurements of the refractive index dispersion showed a composition dependance only for the extraordinary beam. The Curie temperature of the ferroelectric phase transition 4 m mm → 4 mm determinated by calorimetric measurements exhibited a clear composition dependance. It is expected that in the complete mixed crystal system Ca x Sr y Ba 1 - x - y Nb 2 O 6 the Curie temperature could be varied between about 80 ∘ C for strontium barium niobate with x Sr = 0.61 and about 300 ∘ C for CBN with x Ca ≈ 0.20 , the lowest possible Ca content.

A variety of applications, such as photodynamic therapy, require efficient red-emitting semiconductor lasers with high output power and continuous wave life times >1,000 h. AlGaInP lasers have shown to be the best candidates in this spectral range. However, compared to infrared emitters, high-power performance is still limited by major degradation effects, especially by catastrophic optical damage (COD). COD in AlGaInP lasers has hardly been researched in the past. We employed an innovative combination of concepts, namely microphotoluminescence (μPL) mapping and focused ion beam (FIB) microscopy to investigate the COD induced defects in AlGaInP broad-area lasers. High resolution μPL demonstrated that those defects are composed of highly nonradiative complex dislocation networks, which start from the output facet and propagate in form of branches inside the cavity. Moreover, FIB analysis showed that those dark line defects are confined to the active region, containing the quantum wells and the waveguide. In addition, facet temperature changes during COD were analyzed by means of micro-Raman spectroscopy. Although no visible damage at the coated output facet could be observed, an extreme temperature increase in the immediate vicinity of the COD starting point at the laser output facet was detected. This was followed by a sudden temperature decrease afterward. After analyzing several lasers with emission wavelengths between 635 nm and 650 nm, we concluded that in AlGaInP lasers, absorption of stimulated photons at the laser facet is the major source of facet heating, and that a critical facet temperature must be reached in order for COD to occur. This understanding of nature and behavior of COD is a key element for further improvement in efficiency of high-power diode lasers.

The switch-over to the use of flip-chip Si integrated circuit bonding techniques has been driven by a need to develop higher power and lower voltage devices, capable of carrying larger currents with greater reliability. With the increased use of solder bump interconnections, an understanding of the behaviour of commonly used electroless nickel under bump metallization (UBM) layers is becoming ever more crucial. The aim of this paper is to evaluate the usefulness of white beam synchrotron X-ray topography (WBSXRT) for non-destructive evaluation of the induced mechanical stresses on Si substrates for different Ni(P) based UBM sizes and thicknesses. It is shown that WBSXRT is a powerful tool for non-destructively mapping strain and/or defect distributions within the underlying silicon substrate. Using this technique, it was also found that the crystalline misorientation induced in the underlying silicon is increased for larger UBM diameters. Stress magnitudes in the Si substrate directly under the UBM can reach values as high as 260MPa.

X-ray diffraction topographs made with synchrotron radiation of an epitaxial InAs structure show images of dislocations and stacking faults. Three types of dislocations are identified and their Burgers vectors are determined from a number of topographs having different diffraction vectors and recorded on the same film at a time. Straight dislocations are found to be edge dislocations and their Burgers vector is 〈 1 1 0 〉 . Also mixed dislocations are found. The overall dislocation density is about 2000 cm - 2 . Large stacking faults are limited by long straight dislocations, the Burgers vector of which is 〈 1 1 0 〉 . Only a few threading dislocations are observed in the epitaxial layer grown by vapour-phase epitaxy. Their density is about 500 cm - 2 . Small circular dots found are interpreted as indium-rich inclusions.

InSb p-i-n structures were grown on an undoped InSb wafer in a horizontal metal organic vapour phase epitaxy reactor. 200 to 300 nm thick layers were fabricated using silane and zinc as dopant sources for the n-type and p-type layers, respectively. The defects of these samples were studied using synchrotron X-ray topography in large area transmission and transmission section geometries. Pendellosung fringes typical of a nearly perfect crystal were seen in the transmission section topographs. Large area transmission topographs showed dynamical diffraction images of voids and precipitates. Also straight and circular arc dislocations were observed. Most of the images seen in the topographs arise from the defects in the epilayers. Assuming that all precipitates and voids of the layer have been imaged the average precipitate and void density was calculated to be 4000 cm−2 or 2 × 108 cm−3 in the best sample.

In case of the solution growth of S-doped InP bulk crystals from the In solution the solutal convection plays the dominant role for the transport of matter even under microgravity conditions. A measure for the strength of convection is the macrosegregation. For various boundary conditions the axial segregation is described with modified classical segregation models. The measured and calculated physical parameters such as effective distribution and diffusion coefficients respectively allow a consistent formulation of macro- and microsegragtion.

Dislocations in high quality Heat-Exchanger Method (HEM) produced sapphire were analyzed with the white beam large area transmission synchrotron X-ray topography technique. After analysis the dislocations for different Laue spots, i.e. different diffraction vectors, in one recorded film, three kinds of dislocations, i.e. screw, edge and mixed dislocations were identified in the studied HEM sapphire, but most are mixed type, whose Burgers vectors belong to the two groups of 〈2 1 1 0〉 and 〈1 0 1 0〉 .

Solder-based flip-chip packaging has prompted interest in integrated circuit (IC) packaging applications due to its many advantages in terms of cost, package size, electrical performance, input/output density, etc. The ball grid array (BGA) is one of the most common flip-chip packaging techniques used for microprocessor applications. However, mechanical stresses induced by the flip-chip process can impact adversely on the reliability of products. Synchrotron X-ray topography (SXRT), a non-destructive technique, has been employed to investigate the spatial extent of strain fields imposed on the underlying silicon substrate for Intel® Pentium® III microprocessors due to the lead-tin solder bump process for BGA packaging. Large area and section back-reflection SXRT images were taken before and after a simulation of the reflow process at 350 °C in atmosphere. The presence of induced strain fields in the Si substrate due to the overlying bump structures has been observed via the extinction contrast effect in these X-ray topographs. In addition, orientational contrast effects have also been found after the reflow process due to the severe stresses in the underlying silicon beneath the lead bumps. The estimated magnitudes of stress, |σ|, imposed on the underlying silicon were calculated to be of the order of 100 MPa. The spatial strains in the underlying silicon were relieved dramatically after the lead bumps were removed from the wafer, which confirms that the bumps are indeed a major source of strain in the underlying Si. Finite element modeling (FEM) has also been performed in two-dimensional (2-D) plane strain mode. The magnitudes and spatial distribution of the stresses after the reflow process are in good agreement with the SXRT results.

At the new synchrotron light source ANKA (Angstrom Karlsruhe, Germany) one beamline is optimised for white beam synchrotron topography. First topographs taken at various geometries and materials demonstrate the easy operation and the high resolution. Details about the experimental set-up are given. Large area and section topography in transmission allow a quantitative analysis of the type of dislocations and the dislocation density up to 106 cm−2 which is shown for GaSb:Te and InP:S, respectively. For highly absorbing materials like CdTe the back reflection geometry is adequate to analyse dislocation networks, twins and small angle grain boundaries. The grazing incidence method is used for the characterisation of strain and defects as a function of depth by varying the tilt of the sample which is helpful for processed devices like CdTe strip detectors for X-rays.

Synchrotron X-ray section topographs and etch-pit micrographs of the wafers processed in a CMOS fab, are analyzed and correlated against the measured process-control monitoring data and the device yield obtained from the wafers. The etch-pit micrographs detail precipitates, dislocations, and stacking faults, whereas the X-ray topographs additionally show the strain gradient-caused by lattice bending and misfit. Specifically written image-processing software extracts features from the digitized topographs and micrographs after making computational adjustments. These extracted feature parameters are correlated against the electrically and optically obtained process-control monitoring data, collected from the wafer-processing results, and against the yield obtained from the wafer-probing stage. Several image features extracted from the synchrotron X-ray topographs exhibit a strong correlation to certain measured process parameters, e.g., PMOS transistor threshold voltage, polysilicon sheet resistance, and N-sheet contact chain resistance, rather than with others, like NMOS breakdown voltage, which correlated poorly. As a new result, positive correlation between good device yield and a strong near-surface strain gradient is found by synchrotron X-ray topography. Unexpectedly, computed from the etch-pit micrographs, the yield correlates very poorly to the defect-free zone depth of the wafer surface. The results suggests that strain has more impact on the operation of the electronic device than precipitates solely would have.

Due to the fact that semiconductor devices have decreased significantly in geometry and increased enormously in electronic design complication, flip-chip packaging technology was launched to increase input/output count, improve electrical performance, reduce packaging size and be cost effective. The Intel®Pentium®III microprocessor uses the popular ball grid array (BGA) packaging technique. BGA is one of the most common flip-chip packaging techniques used for microprocessor applications. However, mechanical stresses induced by the flip-chip process are major concerns for the reliability of such devices. Micro-Raman spectroscopy (μRS) is a powerful technique for investigating the spatial extent of strain fields in microelectronic devices. In this study, the strain fields imposed on the underlying silicon substrate due to the lead–tin solder bump process in BGA packaging have been investigated in pre- and post-reflowed samples using μRS and finite element modelling (FEM). For pre-reflowed samples, an approximate uniaxial compressive stress of 200 MPa is developed near the edge of the under bump metallization (UBM). However, a tensile stress up to ~300 MPa is found for post-reflowed samples. Two-dimensional (2D) plane strain FEM has also been performed. The magnitudes and spatial distribution of the stresses after the reflow process are in good agreement with the micro-Raman results.