Improvement in visible luminescence properties of anodized porous silicon by indium plating

Luminescence properties of anodically produced porous silicon (PS) have been improved significantly by depositing In metal into micropores. Thin (approx.300 nm) PS specimens were electrochemically plated in an indium sulfate solution. Observed room-temperature photoluminescence (PL) is very strong in intensity and narrow in spectral width (≥0.22 eV). Furthermore, the photodarkening phenomenon, one of the problems of anodized PS, can be reduced for the In-plated PS, compared with as-anodized PS, while room-temperature PL decay times (approx.10-5s) are slightly longer for the plated PS than those for as-anodized PS and anodically oxidized PS. Possible reasons for the observed improvements are discussed.