Hain Caroline, Wieczerzak Krzysztof, Casari Daniele, Sharma Amit, Xomalis Angelos, Sturm Patrick, Michler Johann, Hessler-Wyser Aïcha, Nelis Thomas
Institute for Applied Laser, Photonics and Surface Technologies, BFH, Bern University of Applied Sciences, Quellgasse 21, Biel/Bienne 2502, Switzerland.
Laboratory for Photovoltaics and Thin Film Electronics, EPFL, École Polytechnique Fédérale de Lausanne, Rue de la Maladière 71b, Neuchâtel 2000, Switzerland.
ACS Appl Nano Mater. 2024 Mar 11;7(6):6242-6252. doi: 10.1021/acsanm.3c06178. eCollection 2024 Mar 22.
This work addresses the need for precise control of thin film sputtering processes to enable thin film material tailoring on the example of zinc tin nitride (ZTN) thin films deposited microwave plasma-assisted high power reactive magnetron sputtering (MAR-HiPIMS). The applied diagnostic techniques (Langmuir probe and energy-resolved time-of-flight mass spectrometry) supported monitoring changes in the deposition environment with respect to microwave (MW) power. During MAR-HiPIMS, the presence of nitride ions in the gas phase (ZnN, ZnN, SnN, SnN) was detected. This indicates that the MW plasma facilitated their production, as opposed to pure R-HiPIMS. Additionally, MW plasma caused post-ionisation of sputtered atoms and reduced the overall energy-per-charge range of incoming charged species. By varying the MW power and substrate biasing, films with comparable chemical compositions (approximately ZnSnN) but different structures, ranging from polycrystalline to preferentially textured, were successfully produced. The application of density functional theory (DFT) further enabled the relationship between the lattice parameters and the optical properties of ZTN to be explored, where the material's optical anisotropy nature was determined. It was found that despite considerable differences in crystallinity, the changes induced in the lattice parameters were subangstrom, causing only minor changes in the final optical properties of ZTN.
这项工作以微波等离子体辅助高功率反应磁控溅射（MAR-HiPIMS）沉积的氮化锌锡（ZTN）薄膜为例，解决了精确控制薄膜溅射工艺以实现薄膜材料定制的需求。所应用的诊断技术（朗缪尔探针和能量分辨飞行时间质谱）有助于监测沉积环境相对于微波（MW）功率的变化。在MAR-HiPIMS过程中，检测到气相中存在氮化物离子（ZnN、ZnN、SnN、SnN）。这表明与纯R-HiPIMS相反，微波等离子体促进了它们的产生。此外，微波等离子体导致溅射原子的后电离，并降低了入射带电粒子的整体能量电荷范围。通过改变微波功率和衬底偏压，成功制备出了具有可比化学成分（约ZnSnN）但结构不同的薄膜，结构范围从多晶到择优织构。密度泛函理论（DFT）的应用进一步使人们能够探索ZTN的晶格参数与光学性质之间的关系，从而确定了该材料的光学各向异性性质。研究发现，尽管结晶度存在显著差异，但晶格参数的变化在亚埃量级，仅导致ZTN最终光学性质的微小变化。
