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The van der Waals material hexagonal boron nitride (hBN) has emerged as a promising candidate for hosting room temperature single-photon emitters (SPEs) for next-generation quantum technologies. However, the requirement of a high temperature anneal (850 °C or higher) to activate the SPEs in hBN makes it difficult to integrate into hybrid structures that cannot tolerate such temperatures, including all silicon-based circuits. In this work, we present a method to deterministically activate quantum emitters in multilayered hBN on a process substrate, followed by a zero thermal budget transfer to a target substrate. This technique does not lead to any degradation or loss of photon purity in the hBN emitters and provides a procedure for combining high-purity emitters with other exciting photonic, magnetic, or electrical properties to explore new physical phenomena. The ability to transfer hBN emitters onto arbitrary substrates creates new technological possibilities to incorporate these quantum photonic properties into photonic integrated circuits and plasmonic devices. [ABSTRACT FROM AUTHOR]

Concurrent in-situ four-point probe resistivity and high resolution synchrotron x-ray diffraction measurements were used to characterize room temperature recrystallization in electroplated Cu thin films. The x-ray data were used to obtain the variation with time of the integrated intensities and the peak-breadth from the Cu 111 and 200 reflections of the transforming grains. The variation of the integrated intensity and resistivity data with time was analyzed using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. For both 111-textured and non-textured electroplated Cu films, four-point probe resistivity measurements yielded shorter transformation times than the values obtained from the integrated intensities of the corresponding Cu 111 reflections. In addition, the JMAK exponents fitted to the resistivity data were significantly smaller. These discrepancies could be explained by considering the different material volumes from which resistivity and diffraction signals originated, and the physical processes which linked these signals to the changes in the evolving microstructure. Based on these issues, calibration of the resistivity analysis with direct structural characterization techniques is recommended. [ABSTRACT FROM AUTHOR]

The microstructural evolution within plated Cu films has been investigated using high-resolution x-ray diffraction, revealing a change in strain state within the recrystallized grains and the surrounding matrix with time. By approximating the case of an isolated grain in a randomly textured material as an Eshelby inclusion in an elastically isotropic matrix, we can determine the elastic strain energy in addition to the interaction strains that develop within the grain due to the effects of elastic anisotropy. The elastic strain energy density generated by a grain possessing cubic symmetry with arbitrary orientation within an elastically isotropic matrix has been compared to that within a fiber-textured film, revealing that the former case possesses less strain energy. These results suggest that the recrystallization of Cu (111) grains from an electroplated film with a small, initial grain size is less energetically favorable for films exhibiting strong (111) texture than for a randomly textured film. Experimental results indicate a sequence that emerges during the recrystallization process: (111) grains grow first, suggesting that the decrease in surface energy provided by the (111) surfaces is larger than the increase in elastic strain energy created by (111) grains. For sufficiently thick films, (100) grains emerge, lowering the strain energy density in the film, after (111) grain growth has saturated because no further decrease in energy is supplied by (111) surface growth. By examining plated Cu films of different thicknesses, we correlate the appearance of recrystallized (100) grains with a threshold energy density based on the additional energy associated with (100) surfaces relative to (111) surfaces. [ABSTRACT FROM AUTHOR]

Sub-monolayer quantities of Mg are introduced in multilayer stacked ZnMgTe quantum dots (QDs) embedded in ZnSe barriers in order to reduce the hole confinement energy by controlling the bandgaps and band-offsets of ZnTe/ZnSe system having type-II band alignment. The photoluminescence (PL) emission from such ZnMgTe/ZnSe QD structure is found to be a broad band centered at 2.35 eV. The higher energy side of the PL band shows a larger blue-shift with increasing excitation intensity and a faster life-time decay due to a greater contribution of the emission from the smaller size dots and the isoelectronic bound excitons. It is found that the characteristic decay time of the PL evolves along the band with a value of 129 ns at 2.18 eV to 19 ns at 2.53 eV. The temperature dependent PL emission is controlled by two thermally activated processes: ionization of electrons away from QD state to the barrier (EA1 ∼ 3 meV) by breaking the type-II excitons and thermal escape of the holes from the ground state to the barrier (EA2 ∼ 114-116 meV). We propose a modified band diagram and energy levels for this ZnMgTe/ZnSe multilayer QD system by determining the composition of Mg inside the QDs and solving the 1-D Schrodinger's equation and show that Mg incorporation lowers the hole activation energy via modification of the valence band offset without changing the barrier significantly. [ABSTRACT FROM AUTHOR]

We report the structural properties and spatial ordering of multilayer ZnMgTe quantum dots (QDs) embedded in ZnSe, where sub-monolayer quantities of Mg were introduced periodically during growth in order to reduce the valence band offset of ZnTe QDs. The periodicity, period dispersion, individual layer thickness, and the composition of the multilayer structures were determined by comparing the experimental high resolution x-ray diffraction (HRXRD) spectra to simulated ones for the allowed (004) and quasi-forbidden (002) reflections in combination with transmission electron microscopy (TEM) results. Secondary ion mass spectroscopy (SIMS) profiles confirmed the incorporation of Mg inside the QD layers, and the HRXRD analysis revealed that there is approximately 32% Mg in the ZnMgTe QDs. The presence of Mg contributes to higher scattering intensity of the HRXRD, leading to the observation of higher order superlattice peaks in both the (004) and (002) reflections. The distribution of scattered intensity in the reciprocal space map (RSM) shows that the diffuse scattered intensity is elongated along the qx axis, indicating a vertical correlation of the dots, which is found to be less defined for the sample with larger periodicity. The diffuse scattered intensity is also found to be weakly correlated along the qz direction indicating a weak lateral correlation of the dots. [ABSTRACT FROM AUTHOR]

Rotation and strain fields were mapped across silicon-on-insulator (SOI) regions induced by overlying stressed Si3N4 features using x-ray nanobeam diffraction. The distribution in SOI tilt exhibited an antisymmetric distribution with a maximum magnitude of 7.9 milliradians, representing one of the first direct measurements of the lattice tilt conducted in situ within buried layers using a spot size of less than 100 nm. The measured rotation distribution corresponds to simulated values generated by boundary element method modeling, indicating that the strain transfer into the underlying SOI primarily induces elastic deformation. [ABSTRACT FROM AUTHOR]

Time-resolved in situ x-ray diffraction measurements were used to study the room-temperature recrystallization kinetics of electroplated copper thin films with thicknesses between 400 and 1000 nm. The thinnest films exhibited limited recrystallization and subsequent growth of grains, while recrystallized grains in the thicker films grew until all as-plated microstructure was consumed. For all films, recrystallized grains that belonged to the majority texture component, <111>, started growing after the shortest incubation time. These grains exhibited volumetric growth until they achieved the film thickness. After this point the growth mode became planar, with the <111>-type grains growing in the plane of the film. Grains with the <100> direction normal to the film surface started growing after the <111>-type grains switched to planar growth. However, the planar growth of this texture component finished at the same time as the growth of the <111> grains. Profile fitting of the 111 peak permitted the separation of the diffraction signals from recrystallized and as-plated grain populations. The average strains in these two populations, calculated from the peak position of the corresponding {111} reflections, were different, indicating a heterogeneous stress state within this texture component. The increasing volume fraction of recrystallized <111> grains with time was monitored via the variation in the diffracted intensity. This variation could be represented by the Johnson-Mehl-Avrami-Kolmogorov model. [ABSTRACT FROM AUTHOR]

We have used scanning microdiffraction topography to determine the mismatch strains and local strain distributions in silicon-on-insulator substrates with overlying thin film stressor features. Analysis of the data using the edge-force model and the Ewald–von Laue dynamical diffraction theory shows the presence of an exponential strain gradient in the vicinity of the buried SiO2/Si-substrate interface. We show that, for simple geometries, it is possible to deduce the sign of the mismatch strain simply by inspecting the microdiffraction topograph. [ABSTRACT FROM AUTHOR]

We describe the evolution of the x-ray scattering pattern which forms on an area detector when a divergent, coherent nanobeam is diffracted from a perfect or weakly deformed single crystal. We show that the scattering can be considered as virtual diffraction from an angular aperture in reciprocal space; this is analogous to pinhole diffraction in real space. We define an angular Fresnel number, YA, which allows the categorization of the nanodiffraction image into near-field, intermediate-field, and far-field regimes. We provide equations for YA in simple geometries and show that dynamical scattering artifacts are eliminated through wave interference in the far-field image; this is the only regime where direct analysis of the charge coupled device image using geometrical formulae to transform distances to diffraction angles is possible. [ABSTRACT FROM AUTHOR]

Strain distributions within a silicon-on-insulator (SOI) layer induced by overlying compressively stressed Si3N4 features were measured using x-ray microbeam diffraction. A comparison of analytical and numerical mechanical models of the depth-averaged strain distributions to the measured strain profiles in the SOI layer indicated a blanket film stress of -2.5 GPa in the Si3N4 features. A two-dimensional boundary element model, implemented to analyze thin film/substrate systems, reproduced the observed strain distributions better than an edge-force formulation due to the incorporation of loading along the Si3N4/Si interface. [ABSTRACT FROM AUTHOR]

We here report results of high resolution x-ray diffraction, x-ray reflectivity (XRR), as well as optical absorption and reflection measurements on ZnSe samples grown by molecular beam epitaxy, with insertion of planar (δ-) regions of both N as an acceptor dopant and Te as a “co-dopant” to facilitate a p-type doping. We note that to enhance the surface diffusion of Te, migration enhanced epitaxy was adopted in the growth of the “δ-layers;” i.e., Te is deposited in the absence of Zn flux. Structural parameters were extracted by simulating the experimental x-ray diffraction curves using a dynamical model. The results show that only the “δ-layers” (with submonolayer thickness) are rich in ZnTe, while the nominally undoped “spacers” have only a low Te concentration. Moreover, the morphology of the surface and interfaces are studied by XRR. Furthermore, the optical absorption and reflection results show that our samples largely preserve the optical properties of the host material (ZnSe). We note that our results, in particular those on the Te concentration, explain the observed good p-type doping of such samples. [ABSTRACT FROM AUTHOR]

Back-reflection images obtained from single-crystal semiconductor substrates using Laue microdiffraction with medium-to-high energy x rays (10–30 keV) may contain double spots, one strong and one weak, for the higher-energy reflections. Some of the weaker spots originate from the back surface of the sample and are due to dynamic diffraction from a finite crystal. Others may be due to epitaxial thin films on the substrate. The intensity and position of the back-surface peaks depend on the x-ray energy, sample characteristics, and diffraction geometry. We provide a set of simple equations that can be used to calculate the separation of such peak pairs. These equations can be used to identify the peaks from the back surface of the sample. [ABSTRACT FROM AUTHOR]

Heteroepitaxial thin-film features that are lattice matched to the underlying substrate undergo elastic relaxation at the free edges of the feature. To characterize the degree of elastic relaxation, we employed synchrotron-based x-ray diffraction techniques to map the change in lattice spacing in the thin film at a submicron resolution. Measurements were conducted on 0.24-μm thick, heteroepitaxially grown SiGe strips of various widths on Si (001). A comparison of the SiGe diffraction peak positions across the features provides a real-space mapping of the extent of elastic relaxation as a function of linewidth. The resultant in-plane normal film stress measurements were compared to calculated values from several elastic mechanical models to assess their validity in predicting stress distributions within the features. [ABSTRACT FROM AUTHOR]

We used hard x-ray fluorescence and soft x-ray transmission microscopy to quantitatively measure “in situ” Cu/SiO[sub 2] interconnect dimensions down to 0.3 μm dimensions. We describe methods and analysis techniques for measuring submicron linewidths, lengths, and thicknesses with accuracies of 30–60 nm precision. The dimensions and shape of submicron Cu vias, W lines, and a 20 nm Ta liner and an electromigration defect (void) were determined by these methods. These nondestructive techniques promise to be useful for nanometer precision metrology studies of a variety of materials systems. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We studied the energetics and kinetics of microstructural evolution in copper films by estimating the magnitude of various possible driving forces for microstructural change that can be present in the as-deposited film. A driving force of at least 100 J/cm[sup 3] is required to account for the speed at which the grain boundaries move at room temperature. This value cannot be accounted for by only considering the minimization of grain-boundary energy and possible effects related to surface and strain energy as the main driving mechanisms. It is suggested that the additional driving force which is needed to explain the speed at which the grains recrystallize, is originating from a high density of defects within the as-deposited grains. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present an analysis of Bragg-Brentano diffraction spectra from blanket thin (10-20 nm) films of polycrystalline Ir, sputter deposited on thermally oxidized Si wafers. We observed that postdeposition annealing sharpened the Ir diffraction peaks, produced enhanced texture, and resulted in the formation of well-defined thickness fringes that were symmetric around the 111 Ir reflection. Scanning electron microscopy confirmed that the fringes were caused by the increased coherence lengths of the annealed grains. Annealed samples subsequently subjected to reactive ion etching exhibited asymmetric fringe patterns, with lower intensity fringes on the high angle side of the 111 Ir peak. Reannealing these samples restored the symmetric fringes. Analysis of the fringe patterns using simple equations and modeling programs in the public domain yielded valuable structural information about the film and the changes caused by processing. These results were verified by x-ray reflectivity measurements and modeling. We conclude that thickness fringe analysis using standard x-ray systems and simple programs can provide cost-effective process diagnostics for high atomic number thin film structures. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We show that off resonance time-resolved Kerr rotation (TRKR) is a quantitatively accurate tool to measure spin dynamics by demonstrating that TRKR scans yield essentially identical temporal profiles when the probe energy is tuned far below, far above, and on resonance with the bandgap. We further show that the observed symmetry of the Kerr rotation with respect to probe energy detuning is inconsistent with time-dependent perturbation theory in the simplest case and resolve the discrepancy by recognizing that the optical lifetime decreases with excess energy above the band edge transition. [ABSTRACT FROM AUTHOR]

Two regions of interest on a copper/tungsten integrated circuit interconnect were imaged using two techniques: (a) the absorption spectrum was measured at 15 x-ray energies between 1687 and 1897 eV, and (b) the x-ray fluorescence spectrum was recorded with incident photon energies of 1822, 1797, and 1722 eV. The energies were chosen to optionally excite tungsten and tantalum above their M[sub 5] edges yet stay below the silicon K edge. Four materials in the circuits, tantalum, tungsten, silica, and copper were mapped using both techniques. The two sets of images agree in their main features, but differ for finer features. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Reports on the results of an x-ray diffraction study of dc-magnetron sputtered tungsten thin films. Phase transformation from beta to alpha W; Different stress states in multilayered single-phase films.

We describe a procedure for the morphological characterization of hard-to-image submonolayerquantum dot structures. This procedure employs high resolution x-ray diffraction based reciprocal space mapping, accompanied by rigorous diffraction modeling for precise determination of the morphology of submonolayerquantum dots. Our modelling results and experimental data clearly show that the investigated quantum dots are anisotropically elongated along the [110] orientation. Complementary polarization dependent photoluminescence measurements, combined with our previously reported magneto-photoluminescence data, confirm this conclusion. Our formalism enables direct extraction of structural information of complex embedded three-dimensional structures, which, due to their low electron density contrast with respect to the surrounding host matrix, cannot be readily investigated by traditional electron diffraction techniques. [ABSTRACT FROM AUTHOR]

We introduce pump-probe magneto-orbital spectroscopy, wherein Laguerre-Gauss optical pump pulses impart orbital angular momentum to the electronic states of a material and subsequent dynamics are studied with 100 fs time resolution. The excitation uses vortex modes that distribute angular momentum over a macroscopic area determined by the spot size, and the optical probe studies the chiral imbalance of vortex modes reflected off the sample. First observations in bulk GaAs yield transients that evolve on time scales distinctly different from population and spin relaxation, as expected, but with surprisingly large lifetimes. [ABSTRACT FROM AUTHOR]

Discusses a cost-effective method, based on x-ray fluorescence imaging and coordinate transforms, for minimizing the sphere-of-confusion error of x-ray microdiffractometers. Maintenance of a sample position to within plus or minus six millimicron over all rotations; Mapping of the grid held in place on the specimen surface.

High resolution x-ray diffraction based reciprocal space mapping is employed to investigate vertical correlation in submonolayer Zn(Cd)Te/ZnCdSe type-II quantum dots (QDs). The average lateral deviation from one dot to another is found to decrease from 13%-17% to 8%-11% with an increase in QD size. Narrower photoluminescence with a better yield is obtained for the sample with improved vertical correlation, indicating smaller QD size distribution along with partial suppression of non-radiative recombination paths. Observed reduction in radiative lifetimes and supportive calculations demonstrate enhanced hole-hole wavefunction overlap pointing towards possibility of miniband formation, an advantageous feature for an intermediate band solar cell. [ABSTRACT FROM AUTHOR]

Presents the proper elastic equations for an epitaxial bilayer system. Derivation of the equations for the case that the misfit strain has not been relaxed by the formation of misfit dislocations in a film; Relation between the film and substrate stress; Equation for the substrate stress.

The strain imparted to 60 nm wide, silicon-on-insulator (SOI) channel regions by heteroepitaxially deposited, embedded silicon-carbon (e-SiC) features was measured using x-ray microbeam diffraction, representing one of the first direct measurements of the lattice parameter conducted in situ in an SOI device channel. Comparisons of closed-form, analytical modeling to the measured, depth-averaged strain distributions show close correspondence for the e-SiC features but 95% of the predicted strain in the SOI channel. Mechanical constraint due to the overlying gate and the contribution of SOI underneath the e-SiC in the diffracting volume to the measurements can explain this difference. [ABSTRACT FROM AUTHOR]

Radiation induced structural damage is observed in silicon-on-insulator (SOI) and SiGe on SOI samples illuminated with monochromatic (11.2 keV) x-ray microbeams approximately 250 nm in diameter. The x-ray diffraction peaks from the irradiated layers irreversibly degrade with time, indicating permanent structural damage to the crystal lattice. The size of the damaged regions is almost an order of magnitude larger than the beam size. The magnitude of damage decreases as one moves away from the center of the illuminated volume. We discuss the threshold dosage required for damage initiation and possible mechanisms for the observed damage. [ABSTRACT FROM AUTHOR]

Real-space maps of strain within silicon-on-insulator (SOI) features induced by adjacent, embedded shallow-trench-isolation (STI) SiO2 regions were obtained using x-ray microbeam diffraction. The quantitative strain mapping indicated that the SOI strain was largest at the SOI/STI interface and decreased as a function of distance from this interface. An out-of-plane residual strain of approximately -31μ[variant_greek_epsilon] was observed in the blanket regions of the SOI. A comparison of the depth-averaged strain distributions to the strain profiles calculated from an Eshelby inclusion model indicated an equivalent eigenstrain of -0.55% in the STI regions acting on the SOI features. [ABSTRACT FROM AUTHOR]

The authors report experimental data and modeling results for reflection microbeam x-ray topographs from a Si substrate strained by an overlying pseudomorphic SiGe film edge. The diffracted x-ray intensity from the Si substrate is strongly asymmetric as a function of distance from the film edge. A model of the diffracted intensity based on the classical Ewald–von Laue dynamical diffraction theory for an antisymmetric strain distribution indicates that the asymmetry in the diffracted beam profile is only due to the scattering process; individual intensity maxima in the intensity profile cannot be uniquely ascribed to individual features in the local strain distribution. [ABSTRACT FROM AUTHOR]

Time-of-flight neutron diffraction data from 20 and 0.7 mm thick perfect Si single crystal samples, which exhibit dynamical diffraction effects associated with finite crystal size, are presented. This effect is caused by constructive interference occurring solely from thin layers bounded by the front (entry) and back (exit) surfaces of the sample with no scattering originating from the layers in between, resulting in two distinct peaks observed for each reflection. If the sample is thin and/or the instrument resolution is insufficient, these two peaks can convolve and cause peak shape aberrations which can lead to significant errors in the strain and peak-broadening parameters obtained from a kinematical diffraction analysis. [ABSTRACT FROM AUTHOR]

To determine the effect of low-modulus materials on the thermal stress evolution within interconnect metallization, thermal and residual stresses in copper features, embedded in an organosilicate glass (SiCOH) on a silicon substrate, were measured by x-ray diffraction as a function of temperature and calculated using finite element modeling. The elastic response of the structures was dictated by the thermal expansion mismatch between copper and silicon, the copper and SiCOH elastic moduli, and the composite geometry. The presence of a low-modulus layer between the features and underlying substrate plays a major role in the elastic stress relaxation generated during thermal cycling. [ABSTRACT FROM AUTHOR]

Conventional formulations of thermal stress evolution in interconnect structures usually ignore the interface integrity between the various levels. In this letter we present thermal and residual stress versus temperature data from simple copper thin-film structures on silicon. The results indicate that interconnection models which assume fully elastic behavior and perfectly bonded interfaces may yield inaccurate predictions of the thermo-mechanical response for feature sizes smaller than 10 μm. [ABSTRACT FROM AUTHOR]

Substrate distortions were mapped near pseudomorphically grown SiGe thin film etched lines of various widths from 1.5 to 20 μm on Si(001) and 190 μm diameter Ni dots on Si(111) using reflection x-ray microdiffraction topography. The strain field extended 30–120 times the thickness of the film away from the feature edge. The profile of the enhanced diffracted intensity was found to follow a characteristic curve when the distance from the feature edge is normalized by a mean interaction distance that depends on the feature size. This normalization and the observed strain decay profiles cannot be predicted or modeled using existing micromechanical models. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report x-ray microdiffraction curvature measurements of a (100)-type Si single crystal loaded in four-point bending and provide experimental verification of a procedure for differentiating between anisotropic, elastically bent beams and plates. In general usage, beam and plate components are distinguished by dimensions alone. In mechanics, however, beams and plates are differentiated based on their flexural rigidity and stress state. Since current textbooks do not provide a quantitative technique for selecting the proper constitutive equations for these two types of structures, we suggest the extension of an analysis for isotropic materials originated by Searle [G. F. C. Searle, Experimental Elasticity (Cambridge University Press, Cambridge, 1908), pp. 40-58] and expanded on by Ashwell [D. G. Ashwell, J. R. Aeronaut. Soc. 54, 708 (1950)]. We demonstrate that, by varying the degree of bending of an anisotropic strip, a single specimen can behave as both a beam and a plate, as is predicted by this analysis. [ABSTRACT FROM AUTHOR]

We report real-time, in situ x-ray microbeam measurements of electromigration-induced Cu redistribution, and the concurrent local stress variation in Al(Cu) wires. The data, which were obtained by combining x-ray microtopography with energy-dispersive fluorescence analysis, encompass both the early and late stages of electromigration as well as the postrelaxation stage at high temperature with the current turned off. We observe that both Cu concentration and stress values show unexpected local variations that may reflect the effect of local configuration such as film-substrate interface integrity or microstructure. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We demonstrate the capability of fluorescence x-ray microscopy with a 0.25 μm beam for in situ measurements of Cu-wiring interconnects of submicron dimensions. We are able to measure submicron line widths, lengths, and thicknesses of both Cu and W structures, and a Ta liner in the test vehicle, to the absolute accuracy of 0.03 μm, and a relative accuracy of ∼4% in lateral dimensions, and ∼10% in heights. The shape of a buried electromigration void was also determined. This nanoscale nondestructive characterization technique promises to be powerful for a variety of materials systems. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Reports on the results of an x-ray microdiffraction study of the deformation field surrounding Ni thin film pads on a 111-type Si wafer. Mapping of the strain fields; Determining the positions of the pads.

Analyzes the quantitative measurement of stress transfer behavior in multilayer thin films structures (nickel/ploymide/copper). Use of x-ray stress analysis; Similarity of shape of the stress transfer function with the shear lag model; Comparison between electroplated films and evaporated films.

Investigates the microstructure of strain-relaxed SiGe/Si thin films that relaxed by different dislocation nucleation mechanisms using x-ray microdiffraction. Intensity variations of the angle of the lattice planes with respect to the incident x-ray beams; Average lateral distance between misfit dislocations in a fully strain-relaxed SiGe/Si structure.

This letter describes quantitative nondestructive measurements of multilayer submicron Cu/SiO[sub 2] interconnect structures such as Cu lines, vias, and W lines with lateral dimensions down to 300 nm and electromigration defect structures using scanning transmission x-ray microscopy employing a 0.2 μm x-ray beam. Typical measurement accuracies are ≤60 nm for widths and lengths and ≤10% in height. The high-resolution and nondestructive nature of this technique provide a very powerful probe of physical properties of nanoscale and submicron materials and structures. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report a set of data on the evolution of stress in thin-film metallization wires during the transient region of electromigration. The excellent strain sensitivity of the x-ray microbeam topography technique allows real-time, spatially resolved measurements at the lowest currents reported to date (1.0x10[sup 4]-1.4x10[sup 5] A/cm[sup 2]). While the steady-state results agree qualitatively with the Blech's stress gradient model [I. A. Blech, J. Appl. Phys. 47, 1203 (1976)], the threshold-length product calculated from our data is about 2-3 times smaller than previously reported values. Stress evolution during the transient state displays local fluctuations which cannot be attributed to experimental errors, indicating possible microstructural effects on local flux divergence even in the case of wide, nonbamboo wires. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Tapered capillaries are frequently used as beam-concentrating optics in microbeam x-ray diffraction experiments. The beams exiting such devices are usually highly divergent and may possess nonuniform intensity distributions. In addition, their alignment poses some special challenges. In this article, the effects of these factors on the precision and accuracy of diffraction data are presented. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Intermediate band solar cells (IBSCs) have been predicted to be significantly more efficient than the conventional solar cells, but have not been realized to their full potential due to the difficulties related to the fabrication of practical devices. The authors report here on growth and characterization of Zn(Cd)Te/ZnCdSe submonolayer quantum dot (QD) superlattices (SLs), grown by migration enhanced epitaxy. These QDs do not exhibit formation of wetting layers, which is one of the culprits for the unsatisfactory performance of IBSCs. The ZnCdSe host bandgap is ∼2.1 eV when lattice matched to InP, while the Zn(Cd)Te-ZnCdSe valence band offset is ∼0.8 eV. These parameters make this material system an excellent candidate for a practical IBSC. The detailed structural analysis demonstrates that the process of desorption of Cd and the preferential incorporation of Zn facilitates the formation of unintentional strained ZnSe-rich layer at the QD-spacer interface. The growth conditions have been then optimized so as to obtain high crystalline quality lattice matched SL, by growing intentionally Cd-rich spacers, which strain balanced the SL. The excitation intensity dependent photoluminescence confirmed the type-II nature of these multilayer QD structures, which is expected to suppress nonradiative Auger recombination, and improve the carrier extraction process when implemented in an actual device. [ABSTRACT FROM AUTHOR]

Presents a corrective reprint of the article 'Differentiating between elastically bent rectangular beams and plates' published by the 'Applied Physics Letters' periodical in 2002.

Comments on an article referring to an analysis technique for extraction of thin film stresses from x-ray data. Specification of the strain states; Implications of the procedure for strain stress management; Recommendations for the development of standard procedure in strain stress management.

The (buried) interface between a polycrystalline Al thin-film feature and its substrate (single crystal Si) was characterized with x-ray microdiffraction. Using a focused x-ray beam (effective spot size on the specimen ∼2×12 μm) with the Si 004 reflection, topographic images of the Si around and under the metallization feature were constructed. Comparison with shear-lag model calculations indicate that the interface is not fully coupled despite the absence of surface cracks. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Electromigration-induced stress distributions in 200 μm long, 10 μm wide aluminum conductor lines in 1.5 μm SiO[sub 2] passivation layers have been investigated in real time using synchrotron-based white-beam x-ray microdiffraction. The results show that a steady-state linear stress gradient along the length of the line developed within the first few hours of electromigration and that the stress gradient could be manipulated by controlling the magnitude and the direction of the current flow. From the current density dependence of the steady-state stress gradient, the effective valence Z[sup *] was determined to be 1.6 at 260 °C. From the time dependence of the transient-state stress gradient, the effective grain boundary diffusion coefficient D[sub eff] was estimated to be 8.2×10[sup -11] cm[sup 2]/s at 260 °C using Korhonen’s stress evolution model [M. A. Korhonen, P. Bo\rgesen, K. N. Tu, and C.-Y. Li, J. Appl. Phys. 73, 3790 (1993)]. Both Z[sup *] and D[sub eff] values are in good agreement with the previously reported values. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]