Effects of indium mole fraction on the physical characteristics of magnetron sputtered InxAl1−xN films

• InxAl1−xN films with composition 0.25 ≤ x ≤ 0.86 were grown on Si (111) substrates.
• Crystallinity of the films was improved by increasing the In mole fraction.
• Surface roughness of the films was decreased by increasing the In composition.
• Raman spectroscopy displayed A1 (LO) and E2 (high) modes at x = 0.40 and x = 0.86.
• Electrical resistivity of the films was decreased with increase of the ‘x’.

InxAl1 − xN films with composition 0.25 ≤ x ≤ 0.86 were grown on p-type Si (111) substrates by using reactive magnetron co-sputtering technique in an ambient of argon and nitrogen at 200 °C. X-ray diffraction results at x = 0.25 and x = 0.40 indicated the formation of nanostructured InAlN films along (101) plane with low diffraction intensities. However, by increasing the indium mole fraction ‘x’ from 0.40 to 0.86, crystallinity of the InAlN film was considerably improved along with a change in its preferred orientation towards the c-plane. Surface morphology analysis revealed an under-dense grains structure at x = 0.25, which was changed into a compact structure with increase of the ‘x’ value. Surface roughness of the films exhibited a decreasing trend with increase of the indium contents whereas the Raman spectroscopy analysis specified the existence of A1 (LO) and E2 (high) phonon modes in the films at x = 0.40 and x = 0.86. The Hall measurements indicated n-type nature of InxAl1 − xN film along with a decrease in its electrical resistivity with increase of the indium composition ‘x’. The current–voltage (I–V) characteristics at x = 0.25 displayed Schottky behavior at the metal/film interface which was changed into the ohmic one with increase of indium mole fraction in the film.