This paper attempts to form AlGaN/GaN quantum wire (QWR) network structures on patterned GaN (0 0 0 1) substrates by selective molecular beam epitaxy (MBE) growth. Substrate patterns were prepared along < 1 1 2 0 > - and < 1 1 0 0 >-directions by electron cyclotron resonance assisted reactive-ion beam etching (ECR-RIBE) process. Selective growth was possible for both directions in the case of GaN growth, but only in the < 1 1 2 0 >-direction in the case of AlGaN growth. A hexagonal QWR network was successfully grown on a hexagonal mesa pattern by combining the < 1 1 2 0 >-direction and two other equivalent directions. AFM observation confirmed excellent surface morphology of the grown network. A clear cathodoluminescence (CL) peak coming from the embedded AlGaN/GaN QWR structure was clearly identified. (c) 2004 Published by Elsevier B.V.