Infrared ellipsometry on hexagonal and cubic boron nitride thin films

Infrared spectroscopic ellipsometry (IRSE) over the wavelength range from 700 to 3000 ${\mathrm{cm}}^{\mathrm{-1}}$ has been used to study and distinguish the microstructure of polycrystalline hexagonal and cubic boron nitride thin films deposited by magnetron sputtering onto (100) silicon. The IRSE data are sensitive to the thin-film layer structure, phase composition, and average grain $c$ -axes orientations of the hexagonal phase. We determine the amount of cubic material in high cubic boron nitride content thin films from the infrared optical dielectric function using an effective medium approach.