Fig. 6: Structural properties of the GaSe films.
a HR-XRD 2θ-ω scans of the GaSe film. The light blue (red) lines indicate the positions of the GaSe (sapphire) reflections. b In-plane azimuthal RHEED map of GaSe. The contributions from GaSe and Al2O3 (the second not discernible in the RHEED pattern itself) have been marked with light blue and red circles. The dashed green line indicates the azimuthal linescan from which the intensity distribution shown in Supplementary Fig. 13 is extracted. c Cross-sectional HR-STEM image of a 87 nm-thick GaSe layer recorded along the [10.0] direction. Scale bar: 5 nm. d Filtered zoom-in STEM image showing the stacking of single GaSe layers overlayed with the \({\gamma }^{{\prime} }\)-GaSe crystal structure (top). Schematic models of \({\gamma }^{{\prime} }\)-GaSe (centrosymmetric tetralayer), and β-, ϵ-, δ-, and γ-GaSe (mirror-symmetric tetralayer). e STEM image of the GaSe/sapphire interface. The red dashed box highlights the fuzzy region between GaSe and sapphire. Scale bar: 3 nm.
