The direct formation of mesoscopic surface corrugations on high-index
GaAs substrates during growth by molecular-beam epitaxy is reported. T
he accumulation of microscopic steps on GaAs (210) to produce one-dime
nsional step arrays with a 230 angstrom lateral periodicity is followe
d by reflection high-energy electron diffraction. The surprisingly hig
h uniformity of the resulting mesoscopic step array is directly confir
med by atomic force microscopy. The shape of the steps is imaged by hi
gh-resolution transmission electron microscopy. Being comparable to th
e exciton Bohr radius in GaAs this length scale of the lateral periodi
city is of particular importance for modulating the electronic propert
ies of GaAs-based heterostructures. Pronounced red shifts in the lumin
escence of undoped GaAs/AlAs multilayer structures and an enhanced int
ensity at room temperature are observed. n-type modulation-doped heter
ostructures exhibit an anisotropic conductivity.