High S/N crystallinity measurement and effective defect passivation in silicon nanostructures for third generation photovoltaics

摘要

For application of Si nanostructures to third generation photovoltaics, high S/N measurement of Si crystallinity and effective defect passivation method have been investigated. Here we use Si/SiO2 multiple quantum wells as an example of nanostructure, and show that attenuated total reflectance FTIR (ATR-FTIR) spectroscopy can be applied to detect crystallization of Si with high sensitivity based on the dependence of silicon-hydrogen absorbance peaks on Si crystal face. ATR-FTIR technique, which probes the very surface of samples, was found to be more sensitive to crystallization than Raman spectroscopy. We also show that high-temperature hydrogen annealing is an effective defect passivation method. In particular, the effectiveness of passivation of E′ center in SiO2, which is essential to the solar cells involving tunneling through SiO2, was demonstrated.