Photoluminescence activity of Yang and Secco etched multicrystalline silicon material

Ultraviolet and blue–green photoluminescence (PL) was investigated on multicrystalline silicon (mc-Si) samples chemically etched by Secco and Yang solutions. The samples were characterized by dislocation density (105–106 cm 2). The form of etched pits is triangular with Yang etch and like a honeycomb with Secco etch as observed with a scanning electron microscope (SEM). These textures of mc-Si wafers give a PL activity similar to that obtained with nanostructures of porous silicon (PS) as reported in the literature. The ultraviolet PL spectra observed with Yang etch shift to the blue–green spectrum range when applying Secco etch. In our experiments we have observed 3–5 mmdiameter macro pores separated by a high density of nanowalls. These observations suggest that the origin of the PL activity are quantum dots resulting from the silicon nanocrystallites obtained after few minutes of chemical etching