States of silicon nanoclusters containing carbon impurities

The structural and electronic states of defective complexes in the Si$_{29}$ cluster with the participation of carbon and hydrogen atoms were determined by the method of non-conventional strong binding (MNSB) in combination with the method of molecular dynamics. It is shown that carbon atoms in silicon clusters form a bridge bond with two silicon atoms and localized in a hexagonal position at the center of the cell, forming a defect of the Si$_{29}$ : C$_i$ type. The introduction of hydrogen into a silicon cluster results in the formation of a defective C$_i$–H–Si complex and a decrease of binding energy of the Si$_{29}$ : C$_i$ defect. Based on the calculations, it was found that presence of leads to carbon gives shallow levels in the band gap of nano-silicon, and the defective carbon-hydrogen complex in a hydrogenated cluster, depending on the charge state of the defective complex. Moreover this exhibits both deep and shallow levels.