Atomic Structure of the Stoichiometric GaAs(114) Surface

The stoichiometric GaAs(114) surface has been prepared using molecular beam epitaxy followed by annealing in ultrahigh vacuum. Based on in situ scanning tunneling microscopy measurements and first-principles electronic-structure calculations, we determine the surface reconstruction which we call $\alpha 2(2\times 1)$. Contrary to what is expected for a high-index surface, it is surprisingly elementary. The $(2\times 1)$ unit cell contains two As dimers and two rebonded Ga atoms. The surface energy is calculated as $53\mathrm{meV}/{Å}^2$, which falls well within the range of low-index GaAs surface energies.