Papers by Author: M. Zacharias

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Authors: Andrey Sarikov, M. Voitovych, Igor Lisovskyy, V. Naseka, A. Hartel, D. Hiller, S. Gutsch, M. Zacharias
Abstract: This work is devoted to determination of characteristics of hydrogen effusion from SiH bonds in Si rich silicon oxynitride (SRON) films, obtained by plasma enhanced chemical vapor deposition, as a result of thermal anneals at temperatures from 400 to 800°C. The values of the concentrations of SiH bonds in HSi (Si3nOn) (0 n 3) complexes contributing to the structure of SRON films are obtained from the analysis of infrared absorption spectra in the range of 2000-2400 cm1. The kinetics of the decrease of SiH concentrations as a result of anneals is described in the framework of a model with distributed activation energy of hydrogen emission. The median value and the mean-square deviation of this distribution as well as the attempt frequencies of SiH bond breaks are determined from the comparison of experimental and calculated SiH concentrations in SRON films. These characteristics are compatible with such characteristics found for the case of the depassivation of PbH centers at the Si/SiO2 interfaces. Obtained results are useful for the controlled formation of the layers of Si nanocrystals in dielectric matrix for Si based tandem solar cells applications.
Authors: Olga A. Shalygina, Denis M. Zhigunov, Dmitrii A. Palenov, Victor Timoshenko, Pavel K. Kashkarov, M. Zacharias, Paul M. Koenraad
Abstract: We report on the experimental and theoretical studies of population/depopulation dynamics of excitons in the structures with Si nanocrystals in SiO2 matrix (nc-Si/SiO2) under strong optical excitation. The experimental results are explained using a phenomenological model based on rate equations for coupled system of energy donors (excitons) and energy acceptors (erbium ions). Exciton luminescence is found to exhibit superlinear dependence for Er-doped samples. At the same time the Er-related luminescence at 1.5 μm shows a saturation of the intensity and shortening of the lifetime, which are attributed to the population inversion of the Er ions states. The obtained results demonstrate that nc-Si/SiO2:Er systems can be used for applications in Si-based optical amplifiers and lasers, compatible with planar Si-technology.
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