Influence of oxygen and carbon impurities on the parameters of a silicon cluster in the presence of a vacancy

The influence of vacancies on the structure of silicon clusters Si$_{29}$H$_{36}$ and Si$_{87}$H$_{70}$ modified by the introduction of O and C atoms has been studied with the method of computer simulation in the density functional theory approximation. It has been shown that in a vacancy-free cluster, a complex О$_\mathrm{i}$–Si–C$_\mathrm{i}$ is formed upon the simultaneous introduction of C and O atoms, while in clusters with vacancies, complexes of the 3H+C$_\mathrm{i}$+Si and Si–O–V types are formed. It has been determined that the location of carbon and oxygen depends largely on the nano-cluster size, when oxygen interacting with the vacancy in Si$_{80}$Si$_{70}$ clusters, an A-center is formed. It has been revealed that deep levels may appear due to changes in the electronic states of the silicon cluster, caused by the interaction of technological impurities with the vacancy in the elementary cell of the silicon cluster. It has been established that the simultaneous insert of O and C atoms, the size of the nano-clusters, and the presence of an interstitial silicon atom causes the formation of weakly interacting defective complexes and the migration of hydrogen atoms inside the nano-cluster.