optical characterization of chemically etched nanoporous silicon embedded in sol-gel matrix

Abstract

Nanoporous (NPs) silicon fabricated by chemical etching process in HF acid was first separated in tetrahydrofuran (THF) solvent and then incorporated into SiO2 matrix. The matrix was prepared by sol gel process in which dimethylformamide (DMF) was used as drying chemical control additive (DCCA) to form crack-free dried sample. We examined the optical properties of NPs in three medium which are solvent, sol, and dried sol gel. Our observations reveal that absorption spectra of NPs silicon in THF are modified with respect to the spectra in sol gel. Significant stability in PL of NPs silicon in the sol gel is observed. Influence of matrix environment on peaks of NPs is also discussed. Surface morphology is characterized by field emission scanning electron microscopy (FESEM) which shows that the NPs silicon in THF is similar to the sol gel but becomes aggregation particle to particle. Presence of Si nanoparticles in THF and sol is confirmed by Transmission electron microscopy (TEM). The NPs silicons have mono dispersive and high crystalline nature with spherical shape of around 5 nm in sizes.