Scanning tunnelling microscopy study of Au growth on Mo(110)

Scanning tunnelling microscopy (STM) has been used to investigate the growth behaviour of ultra-thin Au films up to two monolayers thick on a Mo(110) surface at room temperature. An analysis of STM measurements indicates that the layer-by-layer growth for the first two layers of Au is observed. For submonolayer coverage gold prefers to nucleates along the [ 00 1 ¯ ] and [ 1 1 ¯ 1 ] directions and creates one atom high islands on Mo terraces. The average diameter of the observed gold islands is about 12 ± 5 nm. In the completed first layer, no ordered regions were observed. In addition, when the coverage increases to 1.2 ML, the decoration of the substrate steps by one atom high Au islands can be distinguished. As the sample is post-annealed to 800 K, the rearrangement of an existing film did occur and a Au–Mo surface alloy is formed.