Terracing and step bunching in interfaces of molecular beam epitaxy-grown (Al)GaAs multilayers

The growth terraces in molecular beam epitaxy-grown AlxGa1−xAs multilayers are observed on the ultrahigh vacuum cleaved (110) cross-sectional plane using scanning tunneling microscopy. Under regular growth conditions on 2° off oriented vicinal surfaces, we observe step bunching of 2–8 atomic layers and a corresponding extension of the terrace length instead of monolayer steps. These results demonstrate that the roughness of quantum confinement layers can be studied down to the atomic scale in a direct way.