Crystalline nanoscale M₂0₃ (M = Gd, Nd) thin films grown by molecular beam epitaxy on Si(111)

We report the growth, crystal structures, and orientation relationships of nanoscale M₂O₃ (M = Gd, Nd) thin films on Si(111) substrates using molecular beam epitaxy. We find that the grown Gd ₂0₃ and Nd₂O₃ 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]m₂O₃ // [ 111 ]si and [11̄0]M ₂O₃ // [lmacr;10]_si with respect to the Si substrates. Further investigations along in-plane direction show that theM ₂O₃ layers are well matched to the double unit cell of Si substrates, with slightly negative mismatch for the Gd₂O₃ and positive for the Nd₂O₃.