New Chemical Attack of Ag-Catalyzed on Si in HF-H2O2-AGNO3 Medium : (Application to Si Solar Cells Treatment)

The paper presents the investigation of a new three component (HF, AgNO3 and H2O2) metal assisted etching treatment on Si. Future possible applications are in particular the texturization of multicrystalline Si substrates. Currenttreatments of these substrates are known to be complex and moderately effective, especially when diamond wire saws are used for wafer production leaving less surface defects. A first study of the chemical attack of (100) silicon catalyzed by a metal using the above mentioned components is presented. The presence of AgNO3 leads to the deposition of Ag and it is shown that H2O2 re-oxidizes a part of this latter, resulting in different surface structure depending on its concentration. At low H2O2 concentration, the formation of Si nanowires obtained is inhibited in favor of a surface roughness, which makes possible the reduction of the reflectivity. At high concentration of H2O2, Si electro-polishing is obtained with the formation of isolated and well-defined size Ag nanoparticles. These results open new fields of investigation both to the dissolution mechanisms involved and to the potential applications to surface treatments of Si solar cells.