We demonstrate air-stable copper-doped nanostructured borophosphate samples, which were prepared by a facile, low cost, and green synthesis method. The thermal annealing, in a reducing hydrogen atmosphere, enables the formation of metallic copper nanostructures, which was confirmed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and optical absorption. The optical spectra show a main intense surface plasmon resonance (SPR) band centered at 579 nm. The shapes of the nanostructures, morphology, and thickness of the copper nanostructures coating are chosen to be suitable for SERS applications. These samples exhibited very high SERS enhancement factors (EF), depending on thermal annealing time, with excellent reproducibility. The estimated EFs have been found in the range between 10 7 and 10 8 .

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The role played by a kinetic barrier originated by out-of-plane step edge diffusion, introduced in [Leal et al., J. Phys. Condens. Matter 23, 292201 (2011)], is investigated in the Wolf-Villain and Das Sarma-Tamborenea models with short range diffusion. Using large-scale simulations, we observe that this barrier is sufficient to produce growth instability, forming quasiregular mounds in one and two dimensions. The characteristic surface length saturates quickly indicating a uncorrelated growth of the three-dimensional structures, which is also confirmed by a growth exponent β = 1/2. The outof-plane particle current shows a large reduction of the downward flux in the presence of the kinetic barrier enhancing, consequently, the net upward diffusion and the formation of three-dimensional self-assembled structures.