The interfacial roughness of sputtered Fe͓15 Å͔/Au͓21 Å͔ crystalline multilayers on MgO͑001͒ was studied using x-ray specular and nonspecular reflectivity. The nonspecular scattering was collected using an image plate detector that allowed us to map the very weak x-ray diffuse intensity in one in-plane (q x ) and one out-of-plane (q z ) momentum-transfer direction. We have evaluated the interfacial static and dynamic roughness exponents from the in-plane diffuse scattering and the roughness conformality, and found them to be ␣ ϭ0.43Ϯ0.05 and zϭ1.61Ϯ0.15, respectively. From this result we show that the growth of this metallic thin film is described well by the Kardar-Parisi-Zhang ͑KPZ͒ model. By following the evolution of the interfacial roughness of this multilayer, starting from the MgO/Fe/Au heterostructure used to initiate a coherent lattice, we observe a tendency toward saturation in the growth and interfacial smoothing after the deposition of 40 bilayers. This asymptotic smoothing is induced by the mechanisms of the KPZ model and results in a reduction of the interfacial slope as a function of time, according to (t)ϰt Ϫ0.31 . We have also found that the in-plane roughness cutoff length remains finite throughout the multilayer and does not increase to the lateral length of the sample, even after 100 bilayers have been grown.

Effects of low-temperature Si buffer layer thickness on the growth of SiGe by molecular beam epitaxy J. Appl. Phys. 92, 6880 (2002); 10.1063/1.1516842High-quality strain-relaxed SiGe films grown with low temperature Si buffer Relaxed SiGe attracted much interest due to the applications for strained Si/SiGe high electron mobility transistor, metal-oxide-semiconductor field-effect transistor, heterojunction bipolar transistor, and other devices. High-quality relaxed SiGe templates, especially those with a low threading dislocation density and smooth surface, are critical for device performance. In this work, SiGe films on low-temperature Si buffer layers were grown by solid-source molecular-beam epitaxy and characterized by atomic force microscope, double-axis x-ray diffraction, and photoluminescence spectroscopy. It was demonstrated that, with the proper growth temperature and Si buffer thickness, the low-temperature Si buffer became tensily strained and reduced the lattice mismatch between the SiGe and the Si buffer layer. This performance is similar to that of the compliant substrate: a thin substrate that shares the mismatch strain in heteroepitaxy. Due to the smaller mismatch, misfit dislocation and threading dislocation densities were lower.

X-ray diffraction is shown to provide a direct, quantitative, structural measurement of the degree of spontaneous ordering in GaInP. In this paper we combine x-ray diffraction and excitation photoluminescence analyses of CuPt-ordered GaInP, and comparing the results to theoretical predictions for the dependence of the band structure on order parameter, determine the values of the band-gap reduction and crystal-field splitting parameters for the perfectly ordered alloy. ͓S0163-1829͑98͒06447-9͔

The first implementation of fitting X-ray Bragg diffraction profiles from strained multilayer crystals at a remote web-based X-ray software server is presented. The algorithms and the software solutions involved in the process are described. The suggested technology can be applied to a wide range of scientific research and has the potential to promote remote collaborations across scientific communities.

A surfactant-mediated relaxed Si 0.5 Ge 0.5 graded layer with a very low threading dislocation density and smooth surface High-quality strain-relaxed SiGe templates with a low threading dislocation density and smooth surface are critical for device performance. In this work, SiGe films on low temperature Si buffer layers were grown by solid-source molecular beam epitaxy and characterized by atomic force microscope, double-axis x-ray diffraction, photoluminescence spectroscopy, and Raman spectroscopy. Effects of the growth temperature and the thickness of the low temperature Si buffer were studied. It was demonstrated that when using proper growth conditions for the low temperature Si buffer the Si buffer became tensily strained and gave rise to the compliant effect. The lattice mismatch between the SiGe and the Si buffer layer was reduced. A 500 nm Si 0.7 Ge 0.3 film with a low threading dislocation density as well as smooth surface was obtained by this method.