Correlation between structural and optical properties of porous silicon treated with Erbium(III)

This paper highlights a novel passivation approach of porous silicon (pSi) surface through a simple spin coating Erbium (Er) (III) treatment. The effects of Er(III) concentration and annealing temperature on the structural and optical properties of pSi have been investigated. XRD measurements show a significant improvement in the crystallinity of the Er(III) layer and a decrease in the silicon (Si) crystalline size with temperature. Atomic force microscopy (AFM) was used to estimate the surface roughness of the Er-doped pSi layer. Changes of surface chemical composition and spatial distribution of elements in the pSi/Er(III) layer were inspected using Fourier-transform infrared (FTIR) and energy-dispersive X-ray (EDX) spectroscopies. FTIR analysis exhibit a steady enhancing of SiO2 bands accompanied by a dwindling of SiHx bands and the appearance of new bands related to Er–O–Si. Photoluminescence (PL) spectroscopy reveals a sixfold increase in the intensity with the Er(III) concentration and a shift toward the higher energy with the temperature.