Molecular beam epitaxial growth of GaAs on (631) oriented substrates

The homoepitaxy of GaAs on (631)-oriented substrates has been studied as a function of the growth temperature. We observed the spontaneous formation of a high density of large scale features on the surface. The hilly like features are elongated towards the [-5, 9, 3] direction. When the growth temperature was varied from 490 to 580 C the hillocks length exponentially increases from 1.8 to 4.3 mu m, their height linearly increases from 35 to 50nm, and the density exponentially decreases from 2.8 x 10(6) to 3 x 10(5)/cm(2). The hillocks formation is discussed in terms of adatoms diffusion anisotropy, sticking properties at step edges, and Ehrlich-Schwoebel diffusion barriers.