We review our recent results on GaAs sidewall quantum wires, quantum dots and coupled wire–dot arrays fabricated by functional selforganized epitaxy on patterned GaAs(3 1 1)A. The distinct selectivity of (Al,Ga)As growth on patterned GaAs(3 1 1)A allows for strong lateral confinement of photogenerated carriers up to room temperature. Quasi-planar arrays of these semiconductor nanostructures are of unprecedented uniformity, and they can be positioned on the wafer with high accuracy