Structural and Optical Properties of GaSb Films Grown on AlSb/Si (100) by Insertion of a Thin GaSb Interlayer Grown at a Low Temperature

We have investigated the structural and the optical properties of GaSb films with a thin AlSb buffer layer and a GaSb interlayer grown on Si (100) substrates by using molecular beam epitaxy. Reflection high-energy electron diffraction and atomic force microscopy measurements of the thin AlSb buffer layers showed that the surface had uniformly-sized quantum dots with a low defect density. The surface roughness of a GaSb film with a thin GaSb interlayer grown at a low temperature was decreased by a factor of about 5 compared with the roughness of the GaSb film without the thin GaSb interlayer. In addition, double-crystal X-ray diffraction and photoluminescence results showed that the structural and the optical properties of the GaSb layer with the GaSb interlayer were improved significantly. We suggest that the significant reduction of the dislocation density in the GaSb film was clue to the dislocations being prevented from propagating into the GaSb overlayer by the thin GaSb interlayer.