Development of porous silicon matrix and characteristics of porous silicon/tin oxide structures

Porous silicon (PSi) was formed at different current densities in the range of 5–60 mA/cm2 by electrochemical anodized etching in HF for different durations in the range of 10–30 min. Above this PSi structure, SnO2 films were deposited by the spin coating technique. The PSi has been characterized by X-ray diffraction studies. Peaks pertaining to PSi along with those corresponding to SnO2 are observed. Atomic force microscopic studies indicate that very fine needle like silicon nanostructures are observed which is the result of the best PSi structure formed at 30 mA/cm2. For the SnO2 covered PSi structures, larger grains are observed with uniform coverage. The PSi samples prepared at current densities above and below 30 mA/cm2 show PL spectra with asymmetric and overlapped peaks. The PL profile of thin SnO2 film coated on PSi shows a peak at 633 nm and a small hump at about 660 nm.