Table 2: Resume of the process to obtain the samples studied in this work. Si, Ag, and Au implantations were done at 1.5, 1.0, and 1.9 MeV, respectively.

Sample Implantation Steps thermal treatment Thermal treatment A(Ag)* Ag 1 600°C for 1 h in RA A2(Ag)-1* Ag 1 600°C for 1 h in RA A2(Ag)-2* Ag 1 600°C for 1 h in Ar A(Au)-1* Au 1 600°C for 1 h in RA A(Au)-2* Au 1 1100°C for 1 h in RA A(Au)-3* Au 1 1100°C for 1 h in Air

*The samples with metal ion implantation were previously prepared as a sample A or A2 (see Table 1) as indicated in the first letter and number in its label.