Ultra-Large-Scale Step-Free Terraces Formed at the Bottom of Craters on Vicinal Si(111) Surfaces

We report the self-controlled planarization of Si(111) surfaces at the bottom of craters. A (111) plane with a step spacing as large as 10 micrometers can be obtained at the bottom of a crater by heating a misoriented Si(111) substrate with craters at around 1200°C in ultrahigh vacuum. The (111) plane grows preferentially by filling adatoms in the crater until the plane surface reaches one of the top edges of the crater. The resulting surface has an extremely small miscut angle (<0.002°), making it useful for fundamental research into crystal growth as well as for device fabrication.