Among the growth approaches being considered currently to realize quantum dots and quantum wires is the selective epitaxial growth on patterned substrates. With this technique the feature size and geometry are mainly limited by the lithographic process. With optical lithography we achieved a lateral dimension of⩾0.4&mgr;m. Therefore, to further reduce the lateral dimension, but still using optical lithography, the tendency toward facet formation during selective epitaxial growth was investigated. Si0.70Ge0.30multiple quantum well structures with Si0.935Ge0.065spacers and buffers were deposited on (001) Si. The buffer thickness was varied so as to achieve facet junction. While on large areas the Si0.935Ge0.065buffer was relaxed, for dots⩽300&mgr;m or narrower the structures remained strained even for buffer thicknesses exceeding by a factor of two–three the critical thickness of large area. In dots and wires where facet junctioning has taken place a rounded region between facets (approximately 50 nm broad) in the quantum well layers was observed. In wires oriented parallel to⟨100⟩sidewalls self-organized wire formation and vertical correlation of these growth induced wires was observed. The photoluminescence of all dots and wires down to the lowest achieved dimension and including the self-organized wires is strong, with the integral intensity normalized to the surface coverage for 100 nm dots exceeding by a factor of 50 the emission from unpatterned areas. ©1997 American Institute of Physics.