Single-Step Plasma Process Producing Anti-Reflective and Photovoltaic Behavior on Crystalline Silicon

Reactive ion etching (RIE) plasma processes fed with CF4 have been investigated as single-step maskless method for nanotexturing the surface of crystalline silicon. Variation of surface topography under different plasma conditions has been evaluated with scanning electron microscopy and correlated with total, diffuse, and specular reflectance. Chemical features have been evaluated by X-ray photoelectron spectroscopy and current-voltage characteristics have been measured under dark and illuminated conditions. Results indicate that a widely tunable nanoscale texture can be generated onto silicon surface leading to a reduced total reflectance. A significant uptake of carbon and fluorine is detected onto treated silicon with fluorine mainly in ionic form. Further, the plasma modification is per se capable, without further doping procedures, to generate a photovoltaic behavior onto treated silicon, with higher short circuit current in less reflective samples.