Well-aligned InAs quantum dot (QD) arrays are successfully grown on a GaAs ridge structure with a top facet width of 300 nm by using an As 2 source. InAs QDs array at the center of a GaAs ridge by using an As 2 source, while QDs are grown all over a ridge surface by using an As 4 source. This is due to different crystal facets that formed on GaAs ridge structures. GaAs ridge-top structure grown with an As 2 source has V-grooves consisting of (4 1 1)A surfaces, and QDs are grown at the bottom of V-grooves. The ridge structure grown with an As 4 source has (1 0 0)-like surfaces, and QDs are grown on (1 0 0) surface irregularly. InAs QDs on a patterned area have good optical properties with a full-width at half-maximum of 40 meV.