Surface preparation and the evolution of atomically flat step terrace morphology of MgO single crystals

We present a preparation method of vicinal stepped MgO (100) substrate surfaces, a prerequisite for high quality thin film growth. Through atomic force microscopy measurements, the surface morphology evolution of (100)-oriented MgO as a function of the annealing conditions is investigated. In particular, we discuss the effect of temperature, time and ambient atmosphere on the evolution of the MgO surface arrangement. At annealing temperature of 1000°C for 40 min, MgO surface morphology displays an atomically flat, single terminated surface with (100)-oriented, sharp terraces and equidistant steps equal to half of the MgO lattice parameter. Longer annealing leads to the formation of bunched terraces with large step heights of 1-5nm. The optimized recipe developed here efficiently removes surface adsorbates, namely hydroxyl and carbonate groups and restores the terraces on the surface.