Structural and electrical properties of Al_xIn_1-xN (0.10≤x≤0.94) films grown on sapphire substrates

Al_xIn_1–xN films were grown on (0001) sapphire substrates by reactive radiofrequency (RF) magnetron sputtering in an ambient of Ar and N₂. The XRD patterns are shown from Al_xIn_1–xN films grown on AlN/sapphire substrates using a wide range of magnetron power ratio settings. The wurtzite structure films have high crystal quality with full-width at half-maximum (FWHM) in the range of 0.22°–0.52°. The surface morphologies were observed by scanning electron microscopy (SEM). Raman spectra were measured on the Al_xIn_1–xN surfaces in a backscattering configuration at room temperature with 532 nm laser excitation and show A₁(LO) bimodal behavior. Electrical resistivity and electron mobility were measured by the Hall effect method in the conventional Van der Pauw geometry at room temperature. The lowest electrical resistivity is 1 × 10⁻³ Ω·cm. This work suggests that reactive magnetron sputtering is a promising method for growing Al_xIn_1–xN films in over a large composition range.