Position-controlled InAs single/double self-assembled quantum dots (SAQDs) were formed by selective area (SA) metalorganic vapor-phase epitaxy (MOVPE). Narrow GaAs (001)-areas, in the range of 70-200 nm in width/length. were constructed by SA-MOVPE on partially SiNx masked substrates. The number of InAs SAQDs formed on the width-controlled GaAs (001)-facet strongly depends on the width of the top facet. It is also found out that the two-dimensional (2D)-to-3D growth mode transition of InAs in selective MOVPE growth is determined not only by the growth conditions but also by the pattern itself. Different vapor-phase diffusions of source materials depending on the pattern together with dissimilar interfacet surface migration of adatoms are thought to be the origin.