The Role of Interdiffusion and Spatial Confinement in the Formation of Resonant Raman Spectra of Ge/Si(100) Heterostructures with Quantum-Dot Arrays

The phonon modes of self-assembled Ge/Si quantum dots grown by molecular-beam epitaxy in an apparatus integrated with a chamber of the scanning tunneling microscope into a single high-vacuum system are investigated using Raman spectroscopy. It is revealed that the Ge-Ge and Si-Ge vibrational modes are considerably enhanced upon excitation of excitons between the valence band $\Lambda_3$ and the conduction band $\Lambda_1$ (the E1 and E1 + $\Delta_1$ transitions). This makes it possible to observe the Raman spectrum of very small amounts of germanium, such as one layer of quantum dots with a germanium layer thickness of 10 \r{A}. The enhancement of these modes suggests a strong electron-phonon interaction of the vibrational modes with the E1 and E1 + $\Delta_1$ excitons in the quantum dot. It is demonstrated that the frequency of the Ge-Ge mode decreases by 10 cm^-1 with a decrease in the thickness of the Ge layer from 10 to 6 \r{A} due to the spatial-confinement effect. The optimum thickness of the Ge layer, for which the size dispersion of quantum dots is minimum, is determined.Comment: 14 pages, 9 figure

PROGNOSTIC VALUE OF IMMUNOLOGICAL AND GENETIC TESTING IN THE I TRIMESTER OF PREGNANCY COMPLICATED BY SUBCHORIONIC HEMATOMA

Introduction. Pregravid preparation plays a main role in solving issues with recurrent miscarriage and preterm delivery. Detection of etiologic factors of miscarriage with development of preventive strategies seems reasonable.Study objective was to optimize the assessment and treatment algorithms of threatening miscarriage in the I  trimester of pregnancy with subchorionic hematoma formation.Materials and methods. 113 women with subchorionic hematoma were examined in gestational age 4 to 12 weeks. Monitoring of pregnancy till delivery was conducted.Results. The role of the combination of coagulation system genes polymorphisms (II  and V coagulation factors, plasminogen activator inhibitor-1,  methylenetetrahydrofolatereductase) and  altered  level  of  autoantibodies against thyroglobulin in  increased probability of miscarriage was shown.Conclusion. Identification of high risk patients for pregnancy loss in the first trimester by the combination of coagulation system genes polymorphisms and antibody marker of thyroiditis together with a personified therapy approach contribute to the prolongation of pregnancy and reduce the frequency of repeated miscarriage