Stranski–Krastanow (SK) growth mode of layered γ-Na0.7CoO2 on (1 1 1) SrTiO3 substrate

We report the Stranski–Krastanow (SK) growth mode of layered γ-Na0.7CoO2 on (1 1 1) SrTiO3 substrate deposited by pulsed laser deposition method. The γ-Na0.7CoO2 thin film shows SK growth mode with multi-terraces, and nano-islands of ∼30 nm diameter were observed on the terraces. Large terraces with long widths above 100 nm were observed and these terrace heights were close to the lattice constant of unit cell. This large width of the terrace indicates that the surface diffusion of adatoms along the surface is long enough and the kinetics of the step is widespread due to the low deposition rate inhibiting from frequent nucleation of a adatoms. Nano-islands were almost formed on the plane of a terrace in order to release the elastic strain energy due to the lattice misfit.