The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi‐equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.

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Supplementary Text and Figures Supplementary Fig. 1 | Epitaxial growth of (2T)2PbI4-(2T)2PbBr4 lateral heterostructures. ae, Flow diagram showing the epitaxial growth of (2T)2PbI4-(2T)2PbBr4 heterostructures. a, Adding 10 μL of (2T)2PbBr4 precursor solution to grow (2T)2PbBr4 sheets. b, Nucleation of (2T)2PbBr4 sheets with the evaporation of the co-solvents. c, Formation of (2T)2PbBr4 sheets on the substrate after all co-solvents evaporate. d, Adding 10 μL of diluted (2T)2PbI4 precursor solution for the epitaxial growth of (2T)2PbI4 from the existing (2T)2PbBr4 sheets. e, After the co-solvents evaporate, (2T)2PbI4-(2T)2PbBr4 heterostructures are formed on the substrate. The growth of other types of 2D lateral halide perovskite heterostructures follows the same procedures. For clarity, the organic ligands have been omitted. f, Optical image of two (2T)2PbBr4 sheets grown on SiO2/Si substrates. g, Optical image of (2T)2PbBr4-(2T)2PbI4 heterostructures after epitaxial growth of (2T)2PbI4 from the existing (2T)2PbBr4 sheets. The dashed yellow and red frames indicate the outline of (2T)2PbBr4 sheets. The separation between these two square sheets was 4.7 μm initially and narrowed down to 3.9 μm after heterostructure formation. Meanwhile, the lateral length of right sheet was 3.3 μm and increased to 4.1 μm after the heterostructure formation. Above results rule out the possibility of ion exchange mechanism and further validates the epitaxial growth mechanism for 2D halide perovskite lateral heterostructures. h, i, Corresponding PL images of (2T)2PbBr4 sheets and (2T)2PbBr4-(2T)2PbI4 heterostructures. The scale bars are 5 μm.