Seifert Marietta, Rane Gayatri K, Kirbus Benjamin, Menzel Siegfried B, Gemming Thomas
IFW Dresden, SAWLab Saxony, PO Box 270116, 01171 Dresden, Germany.
Materials (Basel). 2015 Dec 19;8(12):8868-8876. doi: 10.3390/ma8125497.
Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under vacuum conditions, leading to a damage of the metallization as well as a change of the properties of the substrate and finally to a failure of the device. Therefore, annealing of bare LGS (La 3 Ga 5 SiO 14 ) substrates at 800 ∘ C under high vacuum conditions is performed to analyze whether this pretreatment improves the suitability and stability of this material for high temperature applications in vacuum. To reveal the influence of the pretreatment on the subsequently deposited metallization, RuAl thin films are used as they are known to oxidize on LGS at high temperatures. A local study of the pretreated and metallized substrates using transmission electron microscopy reveals strong modification of the substrate surface. Micro cracks are visible. The composition of the substrate is strongly altered at those regions. Severe challenges for the application of LGS substrates under high-temperature vacuum conditions arise from these substrate damages, revealing that the pretreatment does not improve the applicability.
对于应用于高温环境的传感器设备而言，具备高温稳定性的衬底材料至关重要。尽管硅酸镧被视作这样一种材料，但在真空条件下进行高温退火时，观察到氧和镓会严重扩散到氧亲和沉积膜中，这不仅导致金属化层受损，还会改变衬底的性能，最终致使器件失效。因此，在高真空条件下对裸LGS（镧镓硅石，La₃Ga₅SiO₁₄）衬底在800℃进行退火处理，以分析这种预处理是否能提升该材料在真空高温应用中的适用性和稳定性。为揭示预处理对后续沉积金属化层的影响，选用RuAl薄膜，因为已知其在高温下会在LGS上发生氧化。利用透射电子显微镜对预处理和金属化后的衬底进行局部研究，结果显示衬底表面发生了显著变化。可见微裂纹，且在这些区域衬底的成分发生了强烈改变。这些衬底损伤给LGS衬底在高温真空条件下的应用带来了严峻挑战，这表明预处理并未提高其适用性。
