The pressure dependence of structure and composition of sputtered AlCrSiTiMoO high entropy thin film

The present study aimed to evaluate the effect of working pressure on the properties of high entropy alloy AlCrSiTiMoO thin film. The layers were deposited by unbalanced DC magnetron sputtering at different working pressures including 1, 4, 8, and 12 mTorr, which is a significant parameter in determining the film properties. The phase formation and crystallinity of AlCrSiTiMoO were evaluated by X-ray diffraction (XRD) method. The morphology and topography of layers were examined by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM), respectively. The morphology of layers with respect to working pressure was almost consistent with the Thornton structure zone diagram although the layer deposited at 1 mTorr owns very smooth surface (S-a = 0.3 nm) with no defect or void within the structure which is very difficult to be placed in any zone presented by the Thornton diagram. The chemical composition of each specimen was measured by energy dispersive spectroscopy (EDS). Based on the results, the amount of oxygen decreased when the pressure increased more than 4 mTorr, while the content of other elements except silicon increased in the coating, which was in good agreement with Simulation of the Metal Transport (SIMTRA). The hardness of deposited films decreased by increasing the pressure which might be related to less energetic neutralized back-scattered argon gas impinging on the substrate surface, which was shown by Static and Dynamic Trim for Sequential and Parallel computer (SDTrimSP) code as well as deposition of atoms with lower energy shown by SIMTRA. The hardness and Young's modulus of the deposited layer at 1 mTorr were equal to 8.9 +/- 0.1 GPa and 196 +/- 2 GPa, respectively. (C) 2020 Elsevier B.V. All rights reserved.