Growth mode and structural properties of GaSb layers grown on silicon substrate by molecular beam epitaxy method are investigated by transmission electron microscopy. It is found that the GaSb grows to three-dimensional islands and grains are tilted to reduce a lattice mismatch through twin boundaries when they are directly grown on Si substrate. A low-temperature (LT) AlSb buffer plays a key role in transferring the growth mode from a three-dimensional island to a layer-by-layer structure. When the LT AlSb layer is used as a buffer, 90° misfit dislocations, with the Burgers vector b of 1∕2a⟨110⟩, are observed on the interface.

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InSb thin films were grown on Si (001) substrate via both conventional one-step growth and two-step growth methods by molecular beam epitaxy. The effect of two-step growth was investigated by transmission electron microscopy. A lot of planar defects and surface steps were observed in the InSb thin film directly grown on buffer layer. The crystalline quality of the InSb thin film was improved when it was grown via two-step growth. The low-temperature InSb initiation layer of two-step growth relieved a misfit strain by generating 90° misfit dislocations and obstructed the propagation of defects by trapping at the interface.

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