Mechanical properties of single-phase Al1-In N films across the compositional range (0≤x≤0.7) grown by radio-frequency magnetron sputtering

Abstract Aluminum indium nitride (Al1−xInxN) films across the compositional range (0 ≤ x ≤ 0.7) were grown on silicon substrate by radio-frequency magnetron sputtering. The In composition was tuned by varying the number of In blocks (nIn) covered on the Al target. We further investigated the dependence of structures, morphologies and mechanical properties on In composition x. It has been found that the as-grown Al1−xInxN films are pure hexagonal phase without phase separation and the (0 0 2) orientation gradually enhances with increasing nIn. While nIn is more than 3, the preferred orientation of Al1−xInxN films would change from (1 0 1) to (0 0 2) plane. Compared with pure AlN film, the Al1−xInxN films exhibit flatter and smoother surface morphology. In addition, the increased nIn leads to a decrease of root-mean-squared (RMS) surface roughness and grain size. All ternary Al1−xInxN films exhibit better mechanical properties than pure AlN film. The hardness and modulus of as-grown Al1−xInxN films tend to decrease when the In composition × is larger than 0.3. The phenomenon can be attributed to the lower density of dislocation and weaker bond energy in Al1−xInxN alloys.