Identification of compressive strain in thin ferroelectric Al1–xScxN films by Raman spectroscopy

Compressive strain in thin ferroelectric Al 1– x Sc x N films with different Sc atom concentrations ( x ) on sapphire substrates was identified by Raman spectroscopy measurement. Both E 2 H and A 1 (LO) spectra showed a blue shift while thinning the Al 1– x Sc x N film thicknesses. The shift was enhanced with higher Sc atom concentration. A stress of the order of 200 MPa was applied from the substrate interface, resulting in a strain of the order of 10 −4 . The presence of the compressive strain at the bottom interface can be correlated to the increase in the coercive field for thinner Al 1– x Sc x N films.