Low-temperature growth of Au on H-terminated Si(111): Instability of hydrogen at the Au/Si interface revealed by non-destructive ultra-shallow H-depth profiling

The initial stage of Au/Si(111)-interface formation has been investigated by hydrogen-specific ultra-shallow depth profiling using nuclear reaction analysis (NRA). via the H-1(N-15,alphagamma)C-12 reaction in grazing incidence, which achieves submonolayer depth resolution. Gold was deposited on the H-terminated Si(111)(1 x 1) substrate at 110 K to suppress Au-silicide formation known to occur at room temperature. The experimental NRA spectrum clearly rules out the prevalence of 14 at the Au/Si(111) interface, even though the reactive Au-Si segregation is inhibited at the low deposition temperature. Nevertheless only similar to30% of the initial H termination layer is desorbed upon deposition of 4.1 Angstrom Au. The shading of the remaining H from the incident N-15 ions by the Au film is analyzed with aid of NRA spectrum simulations, which allows estimating the average of the Au particle size distribution and for exclusion of layer-by-layer growth of An independent from morphological information by surface-imaging.