New insights into crystallographic relation and lattice dynamics effects in {CdO/MgO} superlattices grown by plasma-assisted molecular beam epitaxy

This article explores the structural properties of molecular beam epitaxy grown {CdO/MgO} superlattices on sapphire substrates of different crystallographic orientations (a-, c-, r-, and m-plane). The study involves a comprehensive analysis using X-ray diffraction and Raman spectroscopy.Data attached includes:Figure 1. Schematic drawing of {CdO/MgO} superlattices obtained on a-, c-, m- and r- oriented sapphire substrates.Figure 2. θ/2θ X-ray diffraction patterns for {CdO/MgO} SLs grown on a-, c-, m- and r- plane sapphire substrates.Figure 3. HRXRD 2θ/ω scans of {CdO/MgO} SL structures on a-plane (a), c-plane (b), m-plane (c) and r-plane (d) sapphire substrates. Solid lines represent the experimental data, while dashed lines indicate the simulation results.Figure 4. High resolution XRD reciprocal space maps of symmetrical 111 {CdO/MgO} (a), (b) 220 {CdO/MgO} (c) and 200 {CdO/MgO} (d) reflections of superlattices in samples A, C, M and R, respectively.Figure 5. XRD pole figures of {CdO/MgO} superlattices on a- (a), c- (b), m- (c) and r- (d) plane sapphire substrates.Figure 6. Representation of the epitaxial relationship between Al2O3 substrate of different crystallographic orientations and cubic MgO and CdO layers.Figure 7. (a) Raman spectra of the investigated SL structures grown on Al2O3 substrates of different crystallographic orientations, (b) the example of elaboration of one of the measured Raman bands carried out by fitting the data with Lorentz functions. The laser excitation wavelength was of 532 nm.Figure 8. (a) Raman spectra obtained for the investigated superlattice structures, (b) an analysis of the selected Raman spectrum range carried out by fitting the data with Lorentz functions. The laser excitation wavelength was of 325 nm.