Photoluminescence from C_(60)-coupled porous structures formed on Fe~+-implanted silicon

摘要

(111)-oriented p-type Si wafer with a resistivity of 1-5 OMEGA cm was implanted with Fe~+ and then annealed at 1100 deg C in N_2 for 60 min,followed by anodization in a solution of HF to form porous structure with beta-FeSi_2 nanocrystallites.Photoluminescence (PL) spectral measurements show that a strong PL peak appears in the range of 610-670 nm.The position of the PL peak remains unchanged,but its intensity increases with the storage time in air until about three months and then saturates.C_(60) molecules were chemically coupled on the porous structure through a kind of silane coupling agent to form a nanocomposite.It is revealed that the stable PL peak monotonically shifts to a pinning wavelength at 570 nm.Experimental results from PL,PL excitation,Raman scattering,and x-ray diffraction measurements clearly show that the pinned PL originates from optical transition in C_(60)-related defect states,whereas the photoexcited carriers occur in the beta-FeSi_2 nanocrystallites formed during anodization.This work opens a new way to tailor nanometer environment for seeking optimal luminescent properties.