Epitaxial growth and characterization of ZnGeN 2 by metalorganic vapor phase epitaxy

Abstract

ZnGeN 2 was directly grown on sapphire (1 0 1 ̄ 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 ZnGeN 2 layer was obtained at a growth temperature of 775°C. The epitaxial layer was an orthorhombic structure with the space group of Pna2 1, and the lattice constants were a=0.550±0.020 nm, b=0.644±0.024 nm, and c=0.514±0.025 nm. The epitaxial relationship between the ZnGeN 2 and sapphire substrate was found to be ZnGeN 2(0 4 0)/α- Al 2 O 3 (1 0 1 ̄ 2) and ZnGeN 2[1 0 0]//α- Al 2 O 3 [1 1 2 ̄ 0] . The lattice mismatches to the substrate in ZnGeN 2[0 0 1] and ZnGeN 2[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.