Crystalline Nanoscale M_2O_3 (M = Gd, Nd) Thin Films Grown by Molecular Beam Epitaxy on Si(111)

摘要

We report the growth, crystal structures, and orientation relationships of nanoscale M_2O_3 (M = Gd, Nd) thin films on Si(111) substrates using molecular beam epitaxy. We find that the grown Gd_2O_3 and Nd_2O_3 layers share the cubic bixbyite structure, have single orientations, and are well crystallized. The epitaxial oxides are also found to be of threefold symmetry, having orientation relationships [111]_(M_2O_3) // [11l]_(Si) and [11-bar 0]_(M_2O_3) // [110]_(Si) with respect to the Si substrates. Further investigations along in-plane direction show that the M_2O_3 layers are well matched to the double unit cell of Si substrates, with slightly negative mismatch for the Gd2O_>3 and positive for the Nd_2O_3.