The role of the substrate surface layer in the process of epitaxy part I. the growth of gold films on rocksalt and its substitutional surfaces

Abstract

Chloride, hydroxide and bicarbonate surfaces of rocksalt were produced by vacuum cleavage, water vapour treatment, and combined water vapour—CO₂ treatment of NaC1 single crystals. Epitaxial films of the (100)Au |(100)NaC1 [100]Au| [100]NaC1 orientation were produced on the hydroxide surfaces at 330°c. Polycrystalline films were obtained on both the (bi)-carbonate and chloride surfaces. No effective lowering of the epitaxial temperature was observed in the case of the hydroxide surfaces. It was further proved that treatment at water vapour pressures near saturation is best suited for the epitaxy. Comparison of the different gold films led to the conclusion that air-cleaved rocksalt crystals present mainly hydroxide surfaces.