  A virtual substrate for high quality InAs epitaxial layer has been attained
via metalorganic vapor-phase epitaxy growth of Sb-assisted InxGa1-xAs
metamorphic buffers, following a convex compositional continuous gradient of
the In content from x = 53 % to 100 %. The use of trimethylantimony (or its
decomposition products) as a surfactant has been found to crucially enable the
control over the defect formation during the relaxation process. Moreover, an
investigation of the wafer offcut-dependence of the defect formation and
surface morphology has enabled the achievement of a reliably uniform growth on
crystals with offcut towards the [111]B direction.
