Abstract
Single-crystal Gd 2 O 3 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 Mn 2 O 3 isomorphous cubic structure is identified. The Gd 2 O 3 film aligns its twofold (110) axis with the fourfold (100) surface normal of the substrate, while aligning its [001] and [110] axes with the [011] and [011] 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 18- and 25-Å-thick samples show an elastically strained component in the film, while thicker samples appear fully relaxed, probably through misfit dislocation formation. ©1999 The American Physical Society.