Crystalline Nanoscale M 2 O 3 (M ¼ Gd, Nd) Thin Films Grown by Molecular Beam Epitaxy on Si(111)

Abstract

We report the growth, crystal structures, and orientation relationships of nanoscale M 2 O 3 (M ¼ Gd, Nd) thin films on Si(111) substrates using molecular beam epitaxy. We find that the grown Gd 2 O 3 and Nd 2 O 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 ½111 M2O3 == ½111 Si and ½1 " 1 10 M2O3 == ½ " 1 110 Si with respect to the Si substrates. Further investigations along in-plane direction show that the M 2 O 3 layers are well matched to the double unit cell of Si substrates, with slightly negative mismatch for the Gd 2 O 3 and positive for the Nd 2 O 3