Effects of annealing on the Au/Si(111)-H interface: a high energy and spatial resolution

The interaction between the hydrogenated silicon surface and gold,has been investigated as a function of temperature by means of high resolution core-level photoelectron spectroscopy (PES)and scanning photoelectron microscopy (SPEM).We have studied the e ffect of the annealing on a sample obtained by deposition of 1.5 ML of gold on an in-situ hydrogenated Si(1 11)-7 ·7 substrate.In order to characterize the substrate as well as the adsorbate,both Si 2p and Au4f core-levels have been analysed.Our results show that,after annealing at 550 C,bidimensional (2D)and tridimensional (3D)phases coexist.The two phases have been spectroscopically characterized.On the 3D phase (micrometer sized islands)a bulk-Au component is present in the Au4f7/2 spectrum. We argue that the presence of the hydrogen layer promoted the formation of the islands.We propose a model for the temperature evolution of this interface.