The effect of pulsed laser radiation on a Si layer with a high dose of implanted Ag$^{+}$ ions

With the purpose of creating a thin composite layer of Ag:Si containing Ag nanoparticles (NPs), the effect of a nanosecond pulse produced by ruby laser ($\lambda$ = 0.694 $\mu$m) on single-crystal $c$-Si implanted with a high dose of Ag$^{+}$ ions is studied. The pulsed laser annealing (PLA) is carried out with an energy density exceeding the melting threshold of amorphous $а$-Si ($W\ge$ 1.2 J/cm$^2$). During the PLA, temporal dynamics of reflectivity $R(t)$ of probing laser radiation ($\lambda$ = 1.064 $\mu$m) from the Ag:Si layer is explored and compared to data on the melt existence time obtained by the computer simulation. The morphology of the surface, crystallinity, and spectral optical reflection $R(\lambda) of Ag:Si layers subject to PLA are studied. PLA is found to cause melting and subsequent crystallization of the implanted $а$-Si with ion-synthesized Ag NPs. In addition, a decrease of the surface roughness from 9 to 3--4 nm and redistribution of Ag NP sizes into two fractions--fine (5--15 nm) and larger (40--60 nm)--are observed. The weakening of plasmon intensity Ag NPs in Si ($\lambda_{\mathrm{max}}$ = 835 nm) is observed in $R(\lambda)$ spectra of an Ag:Si layer after PLA as compared with the initial implanted surface. This weakening may be caused by a decrease in concentration of Ag atoms in the immediate proximity to the surface as a result of Ag impurity partial diffusion within the melted layer, as well as Ag partial evaporation during the PLA.