Selective Nucleation and Band-Gap Widening of LiNbO3 Nanocrystals on an α-Al2O3 Substrate

Selective nucleation of LiNbO₃ nanocrystals on the steps was observed during the initial stage of LiNbO₃ film growth in an α-Al₂O₃ (0001) substrate with a multiatomic step structure. In addition, stress stored in the nanocrystals as a result of the different thermal expansion coefficients of the film and the substrate caused band-gap widening. As the size of the nanocrystals decreased, the band gap shifted to a higher energy.