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Dilyara Timerkaeva

Engineering of the light elements in silicon for the photovoltaic application

Published on 10 April 2015

Thesis presented April 10, 2015

Since many years, silicon is the primary semiconductor material in electronic and photovoltaic industry. Intensively studied through decades, its properties are essentially known, however new questions keep arising. We need to achieve deep insight into the numerous possible defects and impurities properties as well as their impacton the performances of the Si based devices. This work covers a range of problems related with point defects interaction of both types long range and short range by means of parameter free first principles calculations.
The former refers to the impact of heavy doping on diffusivity of interstitial oxygen species. The obtained diffusion coefficients as a function of temperature are in a very good agreement with experimental results that demonstrates the validity of the applied methodology. We showed that the enhanced diffusivity in B-doped silicon occurs through a charge transfer mechanism from the p-type dopant. The latter accounts for the various point defect complexes and their thermodynamic, kinetic, and optical properties. Formation of these complexes can be induced by electron irradiation of Czochralski silicon. This aspect is of extreme importance for particular operational environment. Here, we performed a combined experimental-theoretical investigation to identify the impact of isovalent doping (C,Ge) and co-doping (C-Ge, C-Sn, C-Pb) on the production of different complexes (VOi, CiOi, CiCs, etc.), which are electrically and optically active.
Finally, particular attention is addressed to the carbon-carbon defect pair and its properties. Recently, it was established that heavily carbon doped silicon elucidates lasing properties. Here we aimed to revisit the possible forms of the complex and their properties, in order to associate one of them with light emitting G-centre, observed in experiments.

Photovoltaic, Irradiation induced defects, Oxygen diffusion, Defects in silicon

On-line thesis.