rf-sputtered aluminum nitride films on sapphire

Abstract

Single-crystal films of aluminum nitride were fabricated on (0001)- and (011̄2)-oriented sapphire substrates by reactive rf sputtering an aluminum target in ammonia gas. Films sputtered on either sapphire orientation were clear, smooth, and piezoelectric. Effective surface acoustic wave piezoelectric coupling constants as large as k2 = 0.2% were found for films sputtered on (0001)-oriented sapphire.