The spontaneous formation of long chains of quantum dots during the growth of InGaAs/GaAs multiple layers has been reported recently. The effects of In content and spacer on the evolution of dotchains are investigated in the present work. By reducing the In content in the InGaAs layer, the quantum dots in chains are more connected and finally arrays of quantum wires would form. By changing the GaAs spacer layer thickness, the vertical and also lateral spacing between dotchains can be continually tuned. The capability to insert a thick layer of AlGaAs as part of the spacer layer enables us to fabricate InGaAs quantum-dot chains without vertical electronic coupling. The achieved control of self-assembly of organized InGaAs quantum dots may be advantageous for novel optoelectronic applications. (c) 2005 American Vacuum Society.