Structure of Epitaxial Gd203 Films Grown on GaAs (100)

Single crystal Gd sub 2 O sub 3 films were grown epitaxially on GaAs (100) substrate. From the single crystal momentum-space analysis of the x-ray diffraction on four different samples 185, 45, 25 and 18 angstroms thick, an isomorphous Mn sub 2 O sub 3 cubic structure is identified. The Gd sub 2 O sub 3 aligns its surface normal of a two-fold (110) axis with the four-fold (100) surface normal of the substrate, while aligning its [001] and [1 bar 10] axis with the [011] and [01 bar 1] axis of GaAs within the plane, respectively. The absence of the other possible two-fold growth orientation can be explained by the bonding configuration at the interface. The samples 18 and 25 angstrom thick show an elastically strained component in the film, while thicker samples appear relaxed, probably caused by misfit dislocations.