Al rich (111) and (110) surfaces of LaAlO₃

Lanthanum aluminate (LaAlO₃) has garnered significant interests since the discovery of a 2D electron gas at the LaAlO₃/SrTiO₃ interface. In this work, the (110) surface of LaAlO₃ was studied using a combination of transmission electron microscopy plan and profile imaging, image simulation, electron diffraction, X-ray photoelectron spectroscopy, and density functional theory calculations. Profile imaging of the (110) surface was performed on a (111) oriented single crystalline sample with an Al rich surface. Our results indicate that high annealing temperatures (1000–1300 °C) commonly used in preparing well ordered, flat surfaces of LaAlO₃ result in Al rich surfaces. The (110) surface was found to be single layered AlO_x with a (2 × 1) reconstruction. Angle resolved X-ray photoelectron spectroscopy indicated that the (2 × 1) surface structure was not hydrated. Convex hull construction of surface enthalpies as a function of excess AlO_1.5 on the (110) surface was done using density functional theory calculations.