In this work we present the growth and characterization of GaAs self‐assembled quantum wires (SAQWRs), and InAs self‐assembled quantum dots (SAQDs) by molecular beam epitaxy on (631)‐oriented GaAs substrates. Adatoms on the (631) crystal plane present a strong surface diffusion anisotropy which we use to induce preferential growth along one direction to produce SAQWRs. On the other hand, InAs SAQDs were obtained on GaAs(631) substrates by the Stransky–Krastanov (S‐K) growth method. SAQDs grown directly on (631) substrates presented considerable fluctuations in size. We study the effects of growing a stressor layer before the SAQDs formation to reduce these fluctuations.