Investigating Mg-doping on ZnSnN2 ternary thin films via reactive magnetron co-sputtering

This study investigated Mg doping on ZnSnN 2 thin films via the magnetron co-sputtering technique under a high-purity nitrogen background at room temperature. Room-temperature deposition allowed assessment of intrinsic microstructural evolution without thermally driven diffusion, highlighting Mg-induced formation of Mg₃N₂ and Si–N-rich interfacial layers. The discharge power of the magnetron sputtering containing Mg target had the values 0, 120, 140, 160, 180, 200, 220, and 240 W, making eight thin films. In contrast, other growth conditions, such as the N 2 flow rate, discharge currents on the Zn and Sn targets, substrate temperature, and deposition time, were kept constant for all eight films; only the Mg power was varied. The microstructure and morphology, metallic bulk chemical composition ratios, and optical behavior of the deposited ZnSnN 2 thin films were examined by TEM, SEM, XRD, XPS, and Reflectance analysis, where the film properties indicate the formation of Mg 3 N 2 . Although Mg atoms did not seem to substitute in the lattice sites of ZnSnN 2 , there is an indication of possible lattice-interstitial insertions, because of the noticeable changes in their sizes. As confirmed by XRD and cross-section TEM studies, adding Mg has affected grain sizes and resulted in the formation of a Si-N-rich layer at the film-substrate interface. These results provide insight into the role of Mg in defect and interface engineering of ZnSnN₂, offering new directions for display and optoelectronic applications. • Mg-doped ZnSnN₂ thin films were successfully deposited by reactive magnetron co-sputtering at room temperature. • ZnSnN₂ lattice structure remains stable under increasing Mg sputtering power. • Mg incorporation reduces ZnSnN₂ grain size and alters preferred growth orientations. • A Si–N-rich interfacial layer forms due to nitrogen diffusion into the Si substrate. • Optical interference shifts and enhanced reflectance arise from Mg₃N₂ and increased thickness. • Mg incorporation of ZnSnN₂, offering new directions for display and optoelectronic applications.