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 1H(15N, αγ)12C reaction in grazing incidence, which achieves submonolayer depth resolution. Gold was deposited on the H-terminated Si(111)(1 x 1) substrate at 110K to suppress Au-silicide formation known to occur at room temperature. The experimental NRA spectrum clearly rules out the prevalence of H at the Au/Si (111) interface, even though the reactive Au-Si segregation is inhibited at the low deposition temperature. Nevertheless only ∼30% of the initial H termination layer is desorbed upon deposition of 4.1 A Au. The shading of the remaining H from the incident 15N 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 Au independent from morphological information by surface-imaging. (author)