Depth-profiling analysis of ZnO layers with three morphologies by direct-current glow discharge mass spectrometry

In the fabrication of high-quality materials, information regarding the element concentration and distribution in the depth direction is particularly important. In this study, the potential applicability of direct-current glow discharge mass spectrometry (dc-GD-MS) was explored for depth-profiling analysis of zinc oxide (ZnO) layers on steel substrates. The ZnO layers on steel substrates presented three morphologies of thin films, network textures and nanorods fabricated by magnetron sputtering (ZnO-1/steel), sol-gel method (ZnO-2/steel) and hydrothermal synthesis (ZnO-3/steel), respectively. The discharge conditions were optimized based on dc-GD-MS to obtain the ideal depth resolutions. The results revealed that compared with ZnO layers of ZnO-2/steel and ZnO-3/steel, the dc-GD-MS depth-profiling analysis of ZnO-1/steel presented superior performance with depth resolution of 0.22 mu m and a clear interface between ZnO layer and steel substrate. dc-GD-MS depth-profiling analysis suggested that the ZnO layer morphology, thickness and sputtering rate could affect the depth resolution. Furthermore, the fuzzy synthetic evaluation method (FSEM) suggested that the layer morphology had a greater impact on the depth resolutions than thickness and sputtering rate under the optimized discharge conditions. The study presented an efficient and sensitive approach for determining the elemental concentrations and distributions of semi-conducting materials, offering novel insights into material fabrication.