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High-angle annular dark-field (HAADF) imaging and electron energy loss spectroscopy (EELS) in a Cs-corrected scanning transmission electron microscope were utilized to analyze the interfacial atomic structure of InAs/GaSb superlattices (SLs) grown by metalorganic chemical vapor deposition (MOCVD) on InAs substrates. Despite high growth temperature, narrow interface (IF) widths of less than 2.5 monolayers (MLs) and 3.8 MLs were extracted from HAADF and EELS, respectively, indicating that the IF quality of MOCVD-grown InAs/GaSb SLs is comparable to those grown by molecular beam epitaxy. GaAs-type IFs are considered to account for the narrow IF width. In addition, GaSb-on-InAs IFs were found to be sharper and more strained than InAs-on-GaSb IFs, which is correlated with the special gas supply and switching sequence during MOCVD growth. The strain profile deduced from the HAADF image suggests that little Sb is incorporated into InAs sublayers and 7% In is incorporated into GaSb sublayers. [ABSTRACT FROM AUTHOR]

In this study, a femtosecond laser etching method is proposed to pattern an aluminum nitride (AlN) film, grown by metal-organic chemical vapor deposition on sapphire. Via control of typical pulse energies, the designed pattern was precisely written in the AlN film. The morphology of the patterned structures was characterized using a three-dimensional laser scanning confocal microscope and a scanning electron microscope; crystalline quality and film strain were analyzed using a Raman spectrometer and a transmission electron microscope. The results indicate that consistent morphologies were achieved with only slight changes to the crystalline quality. The tensile stress of the AlN film was released, and the film surface was slightly compressed after laser patterning. Thus, femtosecond etching has the potential to be an in situ patterning method during film growth. [ABSTRACT FROM AUTHOR]