A DFT study on the effect of surface termination in CdTe (111)/α-Al2O3 (0001) heteroepitaxy

The heteroepitaxial growth of thin films on complex oxide substrates is highly dependent on chemical interactions in the interfacial material layers. We use first-principle density functional theory calculations to investigate the effect of alterations in the substrate termination in CdTe heteroepitaxy on c-plane sapphire, i. e., α-Al2O3 (0001). Comparing to previous experimental results, we rationalize the observations that an artificial alteration of the surface termination, through the addition of aluminum on the substrate surface, will affect rotational domain alignment. Our findings show that Al adatoms will occupy sites on the sapphire surface that otherwise would be beneficial for the binding of CdTe dimers, effectively altering the orientation of dimers during the initial growth process.