Understanding the microstructural evolution and mechanical properties of transparent Al-O-N and Al-Si-O-N films

Science and Technology of Advanced Materials

Maria Fischer¹  Rowena Crockett¹  Hans Josef Hug¹  Mathis Trant¹  Kerstin Thorwarth¹  Jörg Patscheider² 

[1] Laboratory for Nanoscale Materials Science, Empa, Swiss Federal Laboratories for Materials Science and Technology;Solution Design, Evatec AG;

关键词: aluminum oxynitride;    al-o-n;    aluminum silicon oxynitride;    al-si-o-n;    coatings;    thin films;    transparent;    hard;    microstructure;    reactive sputtering;   

DOI  :  10.1080/14686996.2019.1666425

来源: DOAJ

【 摘 要 】

Optically transparent, colorless Al-O-N and Al-Si-O-N coatings with discretely varied O and Si contents were fabricated by reactive direct current magnetron sputtering (R-DCMS) from elemental Al and Si targets and O2 and N2 reactive gases. The Si/Al content was adjusted through the electrical power on the Si and Al targets, while the O/N content was controlled through the O2 flow piped to the substrate in addition to the N2 flow at the targets. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM), while the elemental composition was obtained from Rutherford backscattering spectrometry (RBS) and heavy ion elastic recoil detection analysis (ERDA). The chemical states of the elements in the coatings were analyzed by X-ray photoelectron spectroscopy (XPS). Based on analytical results, a model describing the microstructural evolution of the Al-O-N and also previously studied Al-Si-N [, , , ] coatings with O and Si content, respectively, is established. The universality of the microstructural evolution of these coatings with the concentration of the added element is attributed to the extra valence electron (e–) that must be incorporated into the AlN wurtzite host lattice. In the case of Al-O-N, this additional valence charge arises from the e – acceptor O replacing N in the AlN wurtzite lattice, while the e – donor Si substituting Al fulfills that role in the Al-Si-N system. In view of future applications of ternary Al-O-N and quaternary Al-Si-O-N transparent protective coatings, their mechanical properties such as residual stress (σ), hardness (HD) and Young’s modulus (E) were obtained from the curvature of films deposited onto thin substrates and by nanoindentation, respectively. Moderate compressive stress levels between −0.2 and −0.5 GPa, which suppress crack formation and film-substrate delamination, could be obtained together with HD values around 25 GPa.

【 授权许可】

Unknown