nan Efremov

Ge Nanoclusters in GeO2: Synthesis and Optical Properties

Ge nanocrystals (NCs) in GeO2 films obtained with the use of two methods were studied. The first method is a film deposition from supersaturated GeO vapor with subsequent dissociation of metastable GeO on heterophase system Ge:GeO2. The second method is growth of anomalous thick native germanium oxide layers with chemical composition GeOx(H2O) during catalytically enhanced Ge oxidation. The obtained films were studied with the use of photoluminescence (PL), Raman scattering spectroscopy, high-resolution electron microscopy (HREM). Strong PL signals were detected in GeO2 films with Ge-NCs at room temperature. “Blue-shift” of PL maximum was observed with reducing of Ge excess in anomalous thick native germanium oxide films. Also a correlation between reducing of the NC sizes (estimated from position of Raman peaks) and PL “blue-shift” was observed. The Ge NCs presence was confirmed by HREM data. The optical gap in Ge-NCs was calculated with taking into account quantum size effects and compared with the position of the experimental PL peaks. It can be concluded that a Ge-NC in GeO2 matrix is a quantum dot of type I.

Divacancy Induced Improvement for Stabilization of Silicon Conductivity versus Temperature

In present work temperature stable conductivity is considered for neutron-doped FZ silicon with point radiation defects. It was shown that divacancy formed after electron irradiation allow to increase resistivity of silicon at room temperature, what lead to less variation of conductivity in a range of temperatures 20-160C. Discrepancy between experimental and theoretical data was evaluated and corrected with introduction in the model deep level center Ec-0.6eV. As result of investigation power resistors were elaborated with 10% deviation from nominal value within the range of temperatures.