Micro-Raman Study of Wurtzite AlN Layers Grown on Si(111)

Abstract

Strain relaxation in cracked wurtzite AIN layers grown on Si(111) substrates was investigated by micro-Raman spectroscopy, under excitations at 2.54 and 3.81 eV. Crack-free areas of the layers exhibit a residual tensile stress, which is evidenced by the redshift of the frequency of the E 2 phonon of AIN. A cartography of the strains in a 0.4 μm thick AIN layer was derived from measurements of the spatial variation of the E 2 phonon frequency. We deduced that the cracking of the AIN layer leads to a relaxation of residual strain of about 60%.