Spiral growth of GaSb on (001) GaAs using molecular beam epitaxy

Atomic force microscopy is employed to obtain images of the surface of GaSb epilayers grown on (001) GaAs using molecular beam epitaxy. The images reveal a surface that consists of micron size mounds that are approximately 4 nm high. A stepped surface is clearly observed on the mounds with a single step edge that originates from a screw dislocation at the center of the mound and moves out to the edge in a spiral fashion. The surface structure of the spiral mounds is observed to depend on the growth temperature of the GaSb epilayer, presumably as a result of a shorter diffusion length of the group III adatoms for lower substrate temperatures.