Microstructure of epitaxial scandium nitride films grown on silicon

Abstract Epitaxial scandium nitride films (225 nm thick) were grown on (1 1 1)-oriented silicon substrates by molecular beam epitaxy (MBE), using ammonia as a reactive nitrogen source. Film microstructure was investigated using X-ray diffraction (XRD). The (1 1 1) ω-scan FWHM of 0.551° obtained for films grown at 850 °C is the lowest reported so far for ScN thin films. The principal orientation of ScN with respect to Si is (1 1 1)ScN//(1 1 1)Si and [ 1 1 ¯ 0 ]ScN//[ 0 1 ¯ 1 ]Si, representing a 60° in-plane rotation of the ScN layer with respect to the Si substrate. However, some twinning is also present in the films; the orientation of the twinned component is (1 1 1)ScN//(1 1 1)Si and [ 1 1 ¯ 0 ]ScN//[ 1 1 ¯ 0 ]Si, representing a ‘cube-on-cube’ orientation. The volume percentage of these twins in the films decreases with increasing film growth temperature.