Effects of anodization current density on photoluminescence properties of porous silicon

Photoluminescence (PL) mechanisms of porous Si (PS) were investigated by comparing FTIR absorption structures with PL properties obtained using a He-Cd laser. PS samples were prepared by anodization at various anodization current densities or by different total electric charge densities. Macroscopic structures were evaluated in the samples. The FTIR and PL results including the evaluation indicate that photoluminescent elements exist in the region of the internal surface of PS pores and the number of elements increases with increasing anodization current densities. The PL peak energies were almost constant among the samples. This is indicative that the minimum size of the quantum-sized crystallites is limited during anodization.