States of silicon nanoclusters containing carbon impurities

Abstract

The structural and electronic states of defective complexes in the Si29 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 Si29 : Ci type. The introduction of hydrogen into a silicon cluster results in the formation of a defective Ci-H-Si complex and a decrease of binding energy of the Si29 : Ci 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. Keywords: MD and MNSB methods, silicon nano-clusters, hydrogenated cluster, structural defects, ab initio methods, carbon and hydrogen atoms, spatial structure, shallow and deep levels.