Surface Effects and Challenges for Application of Piezoelectric Langasite Substrates in Surface Acoustic Wave Devices Caused by High Temperature Annealing under High Vacuum

Materials

Marietta Seifert¹  Gayatri K Rane²  Benjamin Kirbus²  Siegfried B Menzel²  Thomas Gemming² 

[1] IFW Dresden, SAWLab Saxony, PO Box 270116, 01171 Dresden, Germany

关键词: LGS;    Langasite;    RuAl;    high-temperature;    Surface Acoustic Waves;    thin film;   

DOI  :  10.3390/ma8125497

来源: mdpi

【 摘 要 】

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 (LaC 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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.