Silicon Nanoclusters Containing Oxygen, Carbon, and Tellurium Impurities

Abstract Using computer modeling based on the density functional theory approximation, the influence of tellurium atom incorporation and vacancies on the structure of silicon clusters Si 87 H 70 modified with background impurities of O and C was studied. It was shown that in a vacancy-free cluster, the incorporation of a tellurium atom leads to the formation of complexes such as (Si-C i -Si) and (Si-Tei-Si), as well as (2Si-O i -V) and (V-Te i -2Si). In clusters with vacancies, complexes of the types 3Si-C s -V and Si-Te i , as well as (Si-O i -V) and (Te i -2Si), are formed. Computer modeling of the structures of silicon clusters Si 28 H 36 :Te, Si 28 H 36 :[V+Te], Si 86 H 70 :Te, and Si 85 H 70 :[V+Te], performed using the ORCA software package, confirms the dependence of the Te atom’s position within the Si atom matrix on the nanocluster’s size and the manifestation of the Jahn-Teller effect during interaction with a vacancy. Analysis of energy characteristics and electronic levels in the forbidden band of the cluster (E c -0.6358 eV and E c -1.206 eV) indicates that Ci is electrically active. In contrast, under similar conditions, oxygen does not bind to the tellurium atom but instead forms a bond with the vacancy (A-center). Together with the [V-O i ] defect, a [2Si-Te i ] defect with an excess valence electron is formed, creating a deep level (E c -0.5612 eV) in the forbidden band. It was established that simultaneous incorporation of Te and O or C atoms, along with the sizes of nanoclusters and the presence of interstitial silicon atoms, leads to the formation of weakly interacting defect complexes and the migration of hydrogen atoms into the interior of the nanocluster.

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