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Abstract: For the purpose of investigating their structural and optical properties, GaSb thin films and GaSb/AlSb multiple quantum well (MQW) structures were grown on Si(111) substrates. A GaSb/AlSb MQW structure was also grown on Si(001) substrate as a control sample. Surface morphologies and a XRD measurements of GaSb films grown on Si(111) substrates showed that the GaSb film with a 5 nm thick AlSb initiation layer has good crystal quality. Observation of the RHEED patterns of both MQWs suggests that both GaSb films are under tensile strain at growth temperature. In-plane XRD measurement of MQW on Si(111) showed that the (111) face of the GaSb film is aligned to the Si(111) surface upon rotation by 30°. Photoluminescence (PL) spectra consisting of two peaks at 1250∼1400 nm were observed for both MQWs. [Copyright &y& Elsevier]

Abstract: GaSb thin films have been grown on Si(111) substrates by molecular beam epitaxy (MBE), using an Sb template as an initiation layer. The film's crystal properties were investigated by in situ reflection high energy electron diffraction (RHEED), atomic force microscope (AFM), X-ray reciprocal space mapping (RSM) and X-ray diffraction (XRD). RSMs around Si and GaSb 224 reciprocal lattice points indicated that the GaSb thin film grown on the Sb template is nearly unstrained, in contrast to that grown on an AlSb initiation layer which is under tensile strain. The extra peaks on the XRD profiles can be assigned to {224} diffraction originating from a sub-domain region that corresponds to the region rotated by 180° with respect to the fundamental domain of epitaxial film. The very weak intensity of the extra peaks suggests that using the Sb template is an effective way to suppress sub-domain generation in the epitaxial film, resulting in a higher quality GaSb thin film on Si(111) substrates. The spotty RHEED patterns observed were analyzed as a superposition of zinc-blende type diffraction spots on the plane and plane, indicating that the GaSb quantum dots at the initial growth stage are not randomly orientated polycrystalline structures but a two-domain structure with zinc-blende type crystals. [Copyright &y& Elsevier]

Amorphization, following a decrease in the dislocation density and fragmentation of the matrix, has been revealed in a thin layer just below the tensile-fractured surface of a hydrogen-charged ferritic steel. The creation of a high density of vacancies associated with hydrogen is discussed as the origin. [Copyright &y& Elsevier]

Abstract: We have deposited Si-DLC films by pulsed laser deposition using KrF excimer laser, and have investigated etching of the Si-DLC films by atomic hydrogen. We have examined the structure and chemical bonding of the films by Raman spectroscopy, X-ray photoelectron spectroscopy and photoelectron spectroscopy using synchrotron radiation. Photoelectron spectra of Si 2p with 135 eV photons showed two distinguishing components. The main components were identified with Si–C and silicon oxides. The intensity of the oxide component increased when the detection angle to the surface normal was increased from 0 to 60°, indicating that thin oxide layers were formed at the surface. The oxide component decreased by annealing at a substrate temperature above 850 °C in an ultra-high vacuum and it disappeared at 1050 °C. We found that the etching rate of the films drastically decreased by the incorporation of Si. It was also found that the etching rate of the Si-DLC films markedly increased after dipping in a HF solution, indicating that the hydrogen etching of the Si-DLC films is suppressed by thin oxide layers formed at the surfaces. When the HF-treated Si-DLC films were annealed at a temperature above 400 °C in a high vacuum chamber, the etching rate decreased, suggesting that oxide layers were formed again at the surfaces. [Copyright &y& Elsevier]