We present evidence of the new phenomenon of the direct growth of micr
ostructures by metal-organic vapor-phase epitaxy (MOVPE) on high-index
GaAs substrates. One- and zero-dimensional self-faceting by step bunc
hing on GaAs (n11)A substrates produces quantum-wire- and dot-like arr
ays on GaAs (311)A and GaAs (211)A substrates. The lateral periodicity
of self-faceting is controlled by the layer thickness and growth temp
erature and is directly correlated with the red shift of the luminesce
nce of GaAs/AlGaAs heterostructures. On GaAs (n11)B substrates, well-o
rdered quantum-dot arrays are formed in a new self-organizing growth m
ode found in the MOVPE of a sequence of AlGaAs and strained InGaAs fil
ms. The InGaAs film spontaneously interacts with AlGaAs buffer layers
to form ordered arrays of disk-shaped InGaAs quantum dots buried withi
n AlGaAs microcrystals due to lateral mass transport. The size and dis
tance of the disks can be controlled independently by the In compositi
on and the InGaAs layer thickness. Similar structures are also formed
on InP (311)B substrates in the GaInAs/AIInAs and GaInAs/InP material
systems. Lateral confinement of carriers in the disks is confirmed by
the photoluminescence linewidth which, at room temperature, is as narr
ow as 13 meV due to reduced thermal broadening.