Fig. 3

X-ray diffraction experiment for the Bi₂Se₃ thin films in an asymmetric reflection geometry. a, b X-ray diffraction experiment scheme when the Bragg plane of the film is inclined by Δφ with respect to the substrate crystalline plane. c, d X-ray diffraction experiment results for the Bi₂Se₃ film grown on Si nanocrystals (NCs) made on the Si substrate. c shows Bragg peaks of Bi₂Se₃ (006) and Si (004) obtained through ω-2θ scans with different φ optimized to Bi₂Se₃ (006) (open circle) and Si (004) (line). The inclination Δφ is plotted in d as a function of the sample azimuth Φ. e, f X-ray diffraction experiment results for the Bi₂Se₃ film grown on the Al₂O₃ substrate. Bragg peaks of Bi₂Se₃ (006) and Al₂O₃ (006) are obtained through ω-2θ scan with optimized φ to Bi₂Se₃ (006) (open circle) and Al₂O₃ (006) (line) in e. The inclination Δφ is plotted in f as a function of the sample azimuth Φ