Surface topography and optical properties of thin AlN films produced on GaAs (100) substrate by reactive ion-plasma sputtering

A study of the surface topography and optical characteristics of thin AlN films used as passivating and antireflection coatings deposited on $n$-GaAs (100) substrates by reactive ion-plasma sputtering is reported. It was found that the process conditions affect the structure and the optical characteristics of the films, which makes it possible to obtain coatings with prescribed parameters. An analysis of the results furnished by ellipsometry and atomic-force microscopy of the surface shows that the refractive index of the films is correlated with the surface structure.