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Texture evolution is an important issue in materials and nanosciences. Understanding it is fundamental for controlling the final orientation, which in fine controls the desired properties of nanodevices. Here, we reveal the formation of a peculiar texture during the silicidation of nanoscale Pd thin films. We demonstrate that the crystallographic relationship observed between the silicide and the Si(001) substrate, named gyroaxy, evolves continuously and collectively during silicidation. This continuous rotation of the nanosized grains over a wide angular range is proposed to be associated with a diffusional mechanism [ABSTRACT FROM AUTHOR]

Compositional atomic ordering is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report on a method based on x-ray diffuse scattering close to basis forbidden Bragg reflections to infer the lateral location, the symmetry, and the thermal stability of ordered domains in GeSi dome-shaped islands on Si(001) after growth and during annealing. We observe that atomic ordering does not disappear after annealing, demonstrating that it is a resilient metastable phenomenon. [ABSTRACT FROM AUTHOR]

Compositional atomic ordering is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report on a method based on x-ray diffuse scattering close to basis forbidden Bragg reflections to infer the lateral location, the symmetry, and the thermal stability of ordered domains in GeSi dome-shaped islands on Si(001) after growth and during annealing. We observe that atomic ordering does not disappear after annealing, demonstrating that it is a resilient metastable phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: Palladium–silicon (Pd–Si) is a model system for investigating stress development during solid state reaction because of the formation of one single phase (hexagonal Pd2Si). In this work we have measured simultaneously the curvature of the substrate and the diffracted signal from the films during reactive diffusion of a thin Pd (25nm) film with a Si(001) substrate. Only the diffracted signal was measured during the solid state reaction of Pd(25nm) with Si(111). The combined experiment allows monitoring in situ stress and strain during the growth of Pd2Si. The combination method also permits the determination of the elastic constants and thermal expansion coefficient of Pd2Si assuming an equibiaxial stress and isotropical physical properties in Pd2 Si. [Copyright &y& Elsevier]

Plastic relaxation and formation of defects are crucial issues in the epitaxial growth of nanoparticles and thin films. Indeed, defects generate local stress in the crystalline lattice, which affects their surroundings and may lead to undesired effects such as reduced charge-carrier lifetime or nonradiative recombinations. Here, we use a nondestructive method based on x-ray diffuse scattering close to forbidden reflections to identify the defect types with a high sensitivity and quantify their average size and strain field. Combined with transmission electron microscopy, it offers opportunities to track both ensemble average and single defects inside three-dimensional structures. These techniques have been applied to partially embedded and high-Ge-content (xGe=0.87±0.06) dots selectively grown in 20-nm-sized pits on Si(001) surfaces through openings in a SiO2 template. The stress in the 20-nm-wide Ge islands is relaxed not only by interfacial dislocations but also by microtwins and/or stacking faults located at the interface, proving the importance of {111} planes and twinning in the relaxation process of nanometer-size Ge dots. [ABSTRACT FROM AUTHOR]

Plastic relaxation and formation of defects is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report an in situ non-destructive method based on x-ray diffuse scattering close to forbidden reflections to study the formation of defects during the growth of Ge islands on Si(001). The dependence of in-plane spacing between interfacial dislocations, defect size, and density is analyzed as a function of Ge-deposit. It is found that the introduction of additional defects is preferred to relieve strain during growth. [ABSTRACT FROM AUTHOR]

Silicidation of Ni ultra-thin films on Si(001) substrates was investigated from room temperature to 500°C. In situ X-ray diffraction (XRD) experiments were performed to follow the reaction evolution. Transmission electron microscopy (TEM) and atomic probe tomography (APT) analyses highlight the formation of NiSi at low temperature (200°C). A peculiar phase sequence is evidenced for the thinnest deposited Ni film for which the NiSi phase forms from the low temperatures. Structural analyses of the formed silicides indicate that the NiSi phase grows in axiotaxy with the substrate at 200°C whereas NiSi2 rods form at higher temperatures. [ABSTRACT FROM AUTHOR]

Ge-rich and N-doped Ge-Sb-Te thin films and patterned structures for memory applications are investigated in situ during annealing up to 500 °C with a heating rate of 2 °C/min using synchrotron x-ray diffraction. The initial material is amorphous. Under these annealing conditions, Ge crystallization occurs at 340 °C and precedes the one of cubic Ge 2 Sb 2 Te 5 by about 15 °C. In situ monitoring of diffraction allows for a quantification of crystallized quantity, grain size and elastic strain during the material transformation. Increasing N doping reduces the amount of crystallized Ge and Ge grain size. These results bring important insights into the multiphase crystallization of Ge-rich GST phase change materials for memory applications. [Display omitted] • in-situ synchrotron x-ray diffraction at DiffAbs beamline (SOLEIL synchrotron). • Monitoring of crystallization of Ge-rich N-doped Ge-Sb-Te thin films and nanostructures. • Ge crystallizes before GST (15 °C difference in crystallization temperature). • Thermoelastic behavior is different between films and patterned structures and is dominated by Ge. • Nitrogen doping strongly reduces Ge crystallization. [ABSTRACT FROM AUTHOR]