RESUMEN
Today industrial electroplating is mainly carried out using direct current even if the use of modulated currents could offer greats opportunities. Adjusting the amplitude and length of the current's pulses it is possible to control grain size, porosity and homogeneity of the deposits; the use of modulated currents could also decrease the environmental impact of deposition processes as they require a much lower percentage of organic additives. The aim of this work is to assess, through both theoretical and experimental investigation, how the deposition parameters affect the various characteristics of the deposit. We used a commercial acid copper bath for the depositions performing both pulse and reverse pulse sequences. The coatings have been characterised by estimating the deposition yield, homogeneity, hardness and reflectivity. Using pulsed currents, we obtained shinier and brighter films respect to those produced with stationary currents; the deposition efficiency was also improved. Bipolar currents, on the other hand, favour more homogeneous deposits over the entire deposition area, and are less affected by the edge effect.
RESUMEN
CdSe electrodeposition on n-Si (100) substrate was investigated in sulfuric acid solution. The behaviour and the deposition of the precursors (Cd and Se) were studied separately at first. Then, we explored both the alternated deposition, one layer by one, as well as the simultaneous co-deposition of the two elements to form the CdSe semiconductor. Varying the deposition conditions, we were able to obtain nanoparticles, or a thin film, on the surface of the electrode. The samples were then characterised microscopically and spectroscopically with SEM, XRD and XPS. Finally, we evaluated the induced photoemission of the deposit for the application in optoelectronics.