To localize particular zones at the (sub) micrometric scale (50nm-some µm) within the devices can be a major tool to develop new device design. We have investigated this key step in the case of GaAs surfaces, with the requirement to get uniformity for this process on large surfaces in view of the integration of that technology step within a device fabrication process flow. Clean and atomically-flat patterned GaAs surfaces were achieved thanks an original ex situ O2:SF6 microwave plasma treatment combined with an in-situ H-plasma treatment. MBE regrowth was successfully carried out on micro- and nano-stripes along the two perpendicular <011> directions. InAs quantum dot (QD) alignment was achieved along the [-110] stripes after growth of a 7nm-thick Ga0.8In0.2As quantum well used as a stressor on 20nm buffer GaAs. Aligned InAs QD formed upon growth on 7nm GaInAs stressor on oriented [-110] stripes nanopatterned in (001) GaAs.