Effect of ion beam energy on the synthesis of oriented aluminium nitride thin films

Abstract

Polycrystalline aluminium nitride (A1N) thin films were synthesized by evaporation of aluminium and simultaneous irradiation with nitrogen ions, ion-beam assisted deposition, and the effect of the ion beam energy on the film microstructure was studied. The substrate was single-crystal Si(100), and the substrate temperature was varied from room temperature to 573 K. The kinetic energy of the nitrogen ion beam was varied from 0.05 keV to 0.5 keV. The structure of the A1N thin films was examined by X-ray diffraction (XRD). From the XRD patterns, it is found that (1) the (00•2) plane of hexagonal A1N grows preferentially with an ion beam energy of 0.05 keV (the c-axis oriented structure) independently of the substrate temperature, (2) the intensity of the lines (10•0) and (10•1) becomes stronger with increasing ion beam energy, and (3) the full width at half maximum of the (00•2) diffraction line tends to narrow with decreasing ion beam energy and increasing substrate temperature. The present results show that the ion beam energy plays an important role in the degree of preferred orientation of A1N films and c-axis oriented films can be synthesized at room temperature by controlling the ion beam energy.