SiO2的赝晶化及AlN/SiO2纳米多层膜的超硬效应

采用反应磁控溅射法制备了一系列不同SiO₂层厚度的AlN/SiO₂纳米多层膜，利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能，研究了SiO₂层在多层膜中的晶化现象及其对多层膜生长方式及力学性能的影响. 结果表明，由于受AlN六方晶体结构的模板作用，溅射条件下以非晶态存在的SiO₂层在其厚度小于0.6 nm时被强制晶化为与AlN相同的六方结构赝晶体并与AlN形成共格外延生长. 由于不同模量的两调制层存在晶格错配度，多层膜中产生了拉、压交变的应力场，使得多层膜产生硬度升高的超硬效应. SiO₂随层厚的进一步增加又转变为以非晶态生长，多层膜的外延生长结构受到破坏，其硬度也随之降低. 关键词： 2纳米多层膜')" href="#">AlN/SiO₂纳米多层膜 赝晶化 应力场 超硬效应

Effect of SiO2 crystallization on AlN/SiO2 nano-multilayers with superhardness effect

A series of AlN/SiO₂ nano-multilayers with different SiO₂ thickness were prepared by reactively magnetic sputtering. The microstructure of the nano-multilayers was characterized with X-ray diffraction and high-resolution transmission electron microscopy, and a nanoindentor was used to measure their mechanical properties. The phenomenon of crystallization of SiO₂ in the multilayers and its effects on multilayer growth and mechanical properties were studied. Results show that SiO₂, normally amorphous under sputtering condition, was crystallized when thickness was below 0.6 nm due to the effect of hcp crystal structure of AlN. And SiO₂ formed a pseudocrystal structure just the same as AlN and grew epitaxially with AlN on the crystal plane of (0001). Because of the lattice mismatch between two layers, there existed an alternate stress field in the multilayer, which counted for a large portion of the hardness enhancement of the multilayer. Further increasing SiO₂ layers thickness, the coherent interfaces of the multilayers were damaged and SiO₂ become amorphous, accompanying by the decline in the hardness of the films.