Single-crystalline thin films of ScAlMgO4 (SCAM) were fabricated on YSZ (I 11) substrates by reactive solid-phase epitaxy (R-SPE) using ScGaO3(ZnO)(m) (SGZO) single-crystalline buffer layers, which suppress interface reactions between the SCAM layers and the YSZ substrates. First, post-annealing of the SCAM layers fabricated by the R-SPE process was examined. When annealing temperature was raised to > 1200 degrees C, the formation of a spinel MgAl2O4 phase was observed. This is due probably to out-diffusion of Sc ions from the SCAM layers to the YSZ substrates. By introducing an SGZO buffer layer, a single-phase SCAM layer with a step-and-terrace surface was obtained by annealing at 1450 degrees C without the spinel formation. The SCAM layer was grown heteroepitaxially with an epitaxial relationship of (000 1)SCAM // (111)ysz and 010)(SCAM) // (110)ysz. Atomically flat surfaces were eventually formed by chemical-mechanical polishing. The SCAM layer was applied to a lattice-matched buffer layer for the growth of ZnO film, leading to marked lateral growth of ZnO domains. (C) 2007 Published by Elsevier B.V.