MAGNETRON SPUTTERING DEPOSITED AIN WAVE-GUIDES - EFFECT OF THE STRUCTURE ON OPTICAL-PROPERTIES

Aluminium nitride thin films have been deposited on glass substrates by dc magnetron reactive sputtering in Ar + N2 mixtures. Films are studied by waveguide optical methods and a refined X-ray diffraction technique (phase analysis and pole figure analysis). At low pressure the refractive index is high and the films exhibit a strong fibre crystallographic orientation 〈002〉. The optical losses are high due to the roughness of the surface. At high pressure and high current, the films are similar to the low pressure ones but not so highly textured. At low current the index decreases and corresponds to a new growth direction. The c-axis tends to be parallel to the substrate plane. Optical losses become low. These behaviours are interpreted in terms of ion bombardment of the growing film as evidenced by the influence of an rf substrate bias on film growth. © 1990.