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2. Materials Science and Engineering: Heterostructured Systems

(1) Atomic and Electronic Structure at the Interfaces

- GaSb/(AlSb)/Si [Appl. phys. Lett. 88, 241907 (2006)]

: Just eight 90° misfit dislocations appear in the figure. The driving force for the generation of 90° dislocations is the lattice mismatch between the GaSb layer and the Si substrate. 90° dislocations are the most efficient misfit dislocations for strain relaxation.

- BiFeO3/LaAlO3 [J. Appl. phys. 115, 043526 (2014)]

: The strain distribution along the in-plane direction, it is nearly impossible to differentiate the BFO thin film from the LAO substrate, which means that the difference in the lattice parameter along the in-plane direction is zero. In addition, it is also not possible to detect any dislocations near the interface. On the other hand, a complementary color of red and green was detected in Fig. (c), which means that the BFO c-axis lattice parameter is very different from that of LAO.

- Electron-energy loss spectroscopy (EELS)

: The EEL spectra were taken from the films with the monoclinic and the tetragonal phases, respectively. In the spectra for the O K-edge fine structure of metal oxides, there are usually four main feature groups observed.

(2) Microstructure Science and Engineering of Emerging Materials

- GaAs [Appl. Phys. Lett. 100, 133112 (2012)]

: Various structures, including chunks and nanostructures, were observed on the Si(111) substrate. Although the shapes or morphology of the structures are quite different from each other, rounded droplets were detected on most of the structures. Two representative types of 1-D nanostructures were confirmed on the substrate; one with a symmetric hexagonal shape and the other with an asymmetric pentagonal shape.

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