Open AccessCrystallization of Si3N4 on h-AlN and superhardness effect of AlN/Si3N4 nanomultilayers
Author(s) -
Xiaoyan Wu,
Ming Kong,
Geyang Li,
Wei Zhao
Publication year - 2009
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.58.2654
Subject(s) - materials science , amorphous solid , nanoindentation , crystallization , microstructure , nitride , wurtzite crystal structure , transmission electron microscopy , layer (electronics) , diffraction , composite material , crystallography , optics , nanotechnology , chemical engineering , metallurgy , zinc , chemistry , engineering , physics
A series of AlN/Si3N4 multilayers with different Si3N4 thickness were synthesized by reactive magnetic sputtering. The microsructure of the multilayers was characterized with Xray diffraction and highresolution transmission electron microscopy, and nanoindentation was employed to measure their mechanical properties. The crystallization behavior of Si3N4 modulation layer in the multilayers and its influences on the microstructure and mechanical properties of AlN/Si3N4 multilayers were studied. The results show that when Si3N4 thickness is less than about 1 nm, Si3N4, normally amorphous in deposition state, could form a wurtzitetype pseduocrystal structure, same as the structure of hAlN, due to the template effect of AlN crystal layer. Crystallized Si3N4 layers and AlN template layers grow coherently into columnar crystals. Correspondingly, the hardness of the films is enhanced, showing a superhardness effect. Further increasing the thickness of Si3N4 layers, the coherent interfaces of the multilayers are damaged and Si3N4 layers become amorphous, accompanied by the decline in hardness of the films. The discussion indicates that the superhardness effect in AlN/Si3N4 nanomultilayers is related to the enhancement of modulus difference between the two different module layers caused by the alternating stress field in the coherent growth structure.