Heteroepitaxial growth and electric properties of (110)-oriented scandium nitride films

ScN films were grown on MgO(110) substrates and α-Al2O3(101¯0) substrates by a molecular beam epitaxy method, and their crystalline orientation, crystallinity, and electric properties were examined. (110)-oriented ScN films were epitaxially grown on MgO(110) substrates with the same crystal orientations, and ScN films with an orientation relationship (110)ScN || (101¯0)α-Al2O3 and [001]ScN || [12¯10]α-Al2O3 were epitaxially grown on α-Al2O3(101¯0) substrates. Remarkably, electric-resistivity anisotropy was observed for ScN films grown on MgO(110) substrates, and the anisotropy depended on the growth temperature. The carrier concentration and Hall mobility of the ScN films grown on α-Al2O3(101¯0) substrates ranged from 1019-1021 cm-3 and 10-150 cm2 V-1 s-1, respectively. The crystallinity, crystalline-orientation anisotropy, and electric properties of the films were strongly affected by growth conditions. For the growth of ScN films with high mobility on α-Al2O3(101¯0) substrates, a high temperature and an appropriate ratio of source materials were necessary.