The same deposition processes that are used to make amorphous silicon can also be used to make hydrogenated “nano-crystalline” silicon (nc-Si:H). Here fine silicon crystallites with a diameter of several nanometers are bound with a hydrogenated amorphous silicon batter. This nano-crystalline silicon is also referred to as “microcrystalline” silicon for many years.
Below 1.6 eV, nano-crystalline silicon (nc-Si:H) has a stronger optical absorption than a-Si:H, and is similar to c-Si. This makes nc-Si:H interesting as the infrared absorber in multi-junction solar cells, or tandem cells that are sometimes called “micromorph” (Curtins et al. 1987). The Staebler-Wronski degradation is much weaker in nc-Si:H than in a-Si:H, despite the presence of a fraction of a-Si:H.
