Stabilization of photoluminescence properties of silicon nanocrystallites by thermal carbonization of porous silicon

The typical porous silicon (PS) shows an obvious quenching in photoluminescence (PL) properties due to long-term laser radiation [1, 2]. This phenomenon is because of the bonds formation between silicon and hydrogen atoms (Si-H) during the preparation process. These species alter very easily which can result in deterioration of the physical properties like sensing behavior. Many studies have shown the alteration of PL properties as a consequence of exposure to different ambient [3-5]. Therefore, the PL quenching due to low power laser excitation, is a good indicator of variation in the surface bond structures. High-power lasers (~ 40 W/cm²) cause structural damage due to melting of the silicon walls in porous structure while lower-power ones (less than 1 W/cm²) result in a gradual quenching of the photoluminescence intensity. It can be considered that initial meta-stable bond configurations are altered by the influence of low power radiation and make change in PL spectra. Thus fabricated devices based on PS, suffer from lack of stability in case of commercializing of this technology.