The Effect of Pulsed Laser Radiation on a Si Layer with a High Dose of Implanted Ag⁺ Ions

Abstract

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 (λ = 0.694 µm) 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 ≥ 1.2 J/cm²). During the PLA, temporal dynamics of reflectivity R(t) of probing laser radiation (λ = 1.064 µm) 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(λ) 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 (λ_max = 835 nm) is observed in R(λ) 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.