Based on theoretical calculations, we find that the crystal structure of InGaO3 (ZnO)(m) consists of an alternating stack of a wurtzite (Ga/Zn) -O block and an In-O octahedral layer. In the (Ga/Zn) -O block, the Ga atoms favor a modulated boundary structure against a flat boundary structure. The band spectrum shows that hole carriers are spatially confined whereas electrons move more freely through the whole crystal. The characteristics of a superlattice structure appears especially in the flat boundary structure. The band gap decreases with m due to the reduction in the quantum confinement effect. (C) 2008 American Institute of Physics.