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

The growth terraces in molecular beam epitaxy-grown Al,Ga, -As 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.