Abstract

There is an increasing interest in the nitride and oxynitride coatings of aluminum and silicon for optical and microelectronic applications. Silicon nitride as well as aluminum nitride have indices of refraction of 2.1 in the visible region of the spectrum. Silicon oxide and aluminum oxide have indices of 1.45 and 1.65, respectively. Therefore the index of refraction of the coating can be varied by varying the ratio of oxygen to nitrogen in the coating.¹ Important applications are in the fabrication of graded-index optical components such as graded-index antireflection coatings and rugate filters. The ability to tailor the index of refraction has been realized with application of ion beams to the deposition process of optical coatings. Thin films of nitrides, oxynitrides, and oxides of aluminum and silicon have been deposited using ion assisted deposition and ion beam sputtering. Experimental results illustrating the effects of deposition conditions on the optical properties of coatings are presented.

© 1989 Optical Society of America