Structure of epitaxial Gd2O3 films grown on GaAs„100..

Single-crystal Gd2O3 films were grown epitaxially on GaAs~100! substrate. From the single-crystal momentum space analysis on four different samples, 185, 45, 25, and 18 Å thick, a Mn2O3 isomorphous cubic structure is identified. The Gd2O3 film aligns its twofold ~110! axis with the fourfold ~100! surface normal of the substrate, while aligning its @001# and @ 1̄10# axes with the @011# and @011̄# axes of GaAs within the plane, respectively. The absence of the other possible twofold growth orientation can be explained by the bonding configuration at the interface. The 18and 25-Å-thick samples show an elastically strained component in the film, while thicker samples appear fully relaxed, probably through misfit dislocation formation. @S0163-1829~99!08439-8#