Structural variations of Si(1−x)C(x) and their light absorption controllability

The emergence of third-generation photovoltaics based on Si relies on tunable bandgap materials with embedded nanocrystalline Si. One of the most promising approaches is based on the mixed-phase Si(1 − x)C(x). We have investigated the light absorption controllability of nanocrystalline Si-embedded Si(1 − x)C(x) produced by thermal annealing of the Si-rich Si(1 − x)C(x) and composition-modulated superlattice structure. In addition, stoichiometric SiC was also investigated to comparatively analyze the characteristic differences. As a result, it was found that stoichiometric changes of the matrix material and incorporation of oxygen play key roles in light absorption controllability. Based on the results of this work and literature, a design strategy of nanocrystalline Si-embedded absorber materials for third-generation photovoltaics is discussed.