We have obtained a dislocation-free InGaAs layer on Si(111) using micro-channel selective-area metalorganic vapor phase epitaxy. By increasing the supply of the Ga precursor, we removed rotational twins, which have been observed in III-V layers on (111) substrates. From analysis of the atomic structure, the Ga content in the crystal was found to increase gradually as the growth proceeded. This increase resulted in growth in a tilted direction from [111] and extinction of twins. It was concluded that a twin-free InGaAs layer can be obtained when a Ga-rich layer is inserted in the middle of the growth. (C) 2009 The Japan Society of Applied Physics