ZnGeN2 was directly grown on sapphire (10 <(1over bar> 2) substrate by remote-plasma enhanced metalorganic vapor phase epitaxy. The precursors were diethylzinc, monomethylgermane, and excited nitrogen by 2.45 GHz microwave radiation. Single crystalline ZnGeN2 layer was obtained at a growth temperature of 775degreesC. The epitaxial layer was an orthorhombic structure with the space group of Pna2(1), and the lattice constants were a= 0.550+/-0.020nm, b = 0.644+/-0.024 nm; and c = 0.514+/-0.025 nm. The epitaxial relationship between the ZnGeN2 and sapphire substrate was found to be ZnGeN2(0 4 0)/alpha-Al2O3(1 0 (1) over bar 2) and ZnGeN2[1 0 0]//alpha-Al2O3[1 1 (2) over bar 0]. The lattice mismatches to the substrate in ZnGeN2[0 0 1] and ZnGeN2[1 0 0] directions were 1.2% and 12.9%, respectively. The related band-edge and deep level emissions were observed from the photoluminescence measurement. (C) 2003 Elsevier B.V. All rights reserved.