反应溅射VN/SiO_2纳米多层膜的微结构与力学性能

Microstructure and mechanical properties of VN/SiO_2 nanomultilayers synthesized by reactive sputtering

采用V和SiO2靶通过反应溅射方法制备了一系列具有不同SiO2和VN调制层厚的VN/SiO2纳米多层膜.利用X射线衍射、X射线能量色散谱、高分辨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.结果表明:在Ar,N2混和气体中,射频反应溅射的SiO2薄膜不会渗氮.单层膜时以非晶态存在的SiO2,当其厚度小于1nm时,在多层膜中因VN晶体层的模板效应被强制晶化,并与VN层形成共格外延生长.相应地,多层膜的硬度得到明显提高,最高硬度达34GPa.随SiO2层厚度的进一步增加,SiO2层逐渐转变为非晶态,破坏了与VN层的共格外延生长结构,多层膜硬度也随之降低.VN调制层的改变对多层膜的生长结构和力学性能也有影响,但并不明显.

VN/SiO2 nanomuhilayers with different individual SiO2 and VN layer thicknensses were prepared with V and SiO2 targets by reactive sputtering. The microstructure and mechanical properties of the films have been studied by X-ray diffraction, energy dispersive X-ray spectrometry, high-resolution transmission electron microscopy and nanoindentation. The results reveal that the SiO2 film synthesized by radio frequency reactive sputtering in Ar-N2 gas mixture contains no N element, normally amorphous SiO2 is forced to crystallize at very low layer thickness （ 〈 1 nm） , and grows coherently and epitaxially over VN layers. Correspondingly, the hardness of the nanomultilayers increases significantly and reaches a maximum value of 34 GPa. With further increasing in layer thickness, the SiO2 layer gradually forms an amorphous structure and blocks the coherent growth of nanomultilayers, and the hardness of nanomultilayers gradually decreases. On the other hand, the changing of VN layer thickness has relatively small effects on the microstructure and mechanical properties of nanomultilayers.