We report on the selective-area metal-organic vapor-phase epitaxial (SA-MOVPE) growth of GaAs-based periodic air-hole arrays on partially masked GaAs (I I])A substrates for application to two-dimensional photonic crystals (2D PhCs). We obtained uniform I-pin-pitch GaAs 2D air-hole arrays on GaAs (I I I)A substrates with vertical side walls under high AsH3 partial pressure and low-growth-rate conditions. However, under these growth conditions, lateral over-growth (LOG) occurs at three corners of hexagonal air-hole, and the hole shape change to triangle. We clarified the mechanism of selective area growth on a GaAs (I I I)A substrates. We also tried shorter pitch (400nm) GaAs air-hole arrays and AlGaAs SA-MOVPE on GaAs (I I])A. (C) 2004 Elsevier B.V. All rights reserved.