Field-ion scanning tunneling microscopy study of the atomic structure of 6H-SiC(0001) surfaces cleaned by in situ Si molecular beam etching

Field ion-scanning tunneling microscopy has been used to study 6H-SiC(0001) surfaces with Si adlayers on the Si-terminated surface, formed by in situ Si molecular beam etching at 950 °C. The as-cleaned surface showed a (√3×√3) reconstruction. The (2×3), (2√3×6√6), and (3×3) phases were formed by evaporating Si on this clean 6H-SiC(0001)-(√3×√3) surface. A Si(111) film 6 monolayers thick was also epitaxially grown on the 6H-SiC(0001)-(√3×√3) surface at 800 °C, and the surface exhibited the Si(111)-(7×7) reconstruction. A surface vacancy model for the (√3×√3) reconstruction is proposed, and a possible application of utilizing the various surface reconstructions to control the growth of different polytypes of SiC on the 6H-SiC substrate is discussed.