Structure and homoepitaxial growth of GaAs(631)

We have studied the surface atomic structure of GaAs(631), and the GaAs growth by molecular beam epitaxy (MBE) on this plane. After the oxide desorption process at 585°C reflection high-energy electron diffraction (RHEED) showed along the [−120] direction a 2× surface reconstruction for GaAs(631)A, and a 1× pattern was observed for GaAs(631)B. By annealing the substrates for 60min, we observed that on the A surface appeared small hilly-like features, while on GaAs(631)B surface pits were formed. For GaAs(631)A, 500nm-thick GaAs layers were grown at 585°C. The atomic force microscopy (AFM) images at the end of growth showed the self-formation of nanoscale structures with a pyramidal shape enlarged along the [5−9−3] direction. Transversal views of the bulk-truncated GaAs(631) surface model showed arrays of atomic grooves along this direction, which could influence the formation of the pyramidal structures.