Characterization of the annealed (0001) surface of sapphire (al₂o₃) and interaction with silver by reflection electron microscopy and scanning reflection electron microscopy

Annealed (0001) surfaces of singlecrystal sapphire (Al₂O₃) rod have been studied in the electron microscope using reflection electron microscopy (REM), scanning reflection electron microscopy (SREM), and reflection high energy electron diffraction (RHEED). Annealed surfaces of (0001) sapphire are vicinal and characterized by closepacked (0001)oriented terraces separated by faceted multipleheight steps, with edges parallel to energetically preferred lowindex directions (1010and1120). These structural features are not seen on cleaved surfaces or polished surfaces treated at temperatures1,250C. Oxygenannealing produces clean surfaces which prove useful for investigating the interaction of deposited metals with the (0001) sapphire. Both REM and SREM (with microdiffraction spots) techniques have been used to observe fine structure of flat Ag islands on the scale of 1100 nm on the (0001)oriented terraces as well as aggregations at the steps. A preliminary result on interaction with Cu is also included. Copyright1992 WileyLiss, Inc.