Abstract: An overview is given of our investigation of the energy levels and of the correlation functions of the negatively and positively charged excitons (also called trions) in quantum wells in the presence of a perpendicular magnetic field, A detailed comparison is made with available experimental data in III-V and II-VI semiconductor quantum wells. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: We have calculated analytically the spatial distribution of the electric field and current density, and obtained the Joule heat generation rate in a two-dimensional electron gas (2DEG) subjected to a non-homogeneous magnetic field of a 'chess' configuration. The generation of the Joule heat from the 2DEG is mainly concentrated near the singular corners of each 'chess' field and tends to zero in other corners. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract: Infrared absorption spectra of composite precipitates are analysed with a modified Day-Thorpe algorithm, assuming a precipitated phase consisting of a mixture of two components with known optical properties. Additional constraints are introduced when solving the model equations by using a priori knowledge making the algorithm more reliable. It is shown that this novel approach allows determining both morphology and composition of precipitates. The method is applied to characterise oxide precipitates in boron-doped silicon. The results indicate that for the resistivity range above 60 mOmegacm, the precipitated phase is most probably SiO1.17+/-0.14, while for resistivities below 20 mOmega cm, precipitates consist of a SiO2/B2O3 composite with a large volume fraction of B(2)0(3) (up to 40% for 8 mOmegacm material). (C) 2003 Elsevier B.V. All rights reserved.

Abstract: Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mossbauer spectroscopy in silicon materials implanted with Mn-57 ->,Fe-57 ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the Fe-57 Mossbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the Fe-57 hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of Fe-57 ions in substitutional and interstitial sites is proposed. (C) 2014 Elsevier B.V. All rights reserved

Abstract: The envelope function method traditionally employs a single basis set which, in practice, relates to a single material because the k.p matrix elements are generally only known in a particular basis. In this work, we defined a basis function transformation to alleviate this restriction. The transformation is completely described by the known inter-band momentum matrix elements. The resulting envelope function equation can solve the electronic structure in lattice matched heterostructures without resorting to boundary conditions at the interface between materials, while all unit-cell averaged observables can be calculated as with the standard envelope function formalism. In the case of two coupled bands, this heterostructure formalism is equivalent to the standard formalism while taking position dependent matrix elements. (C) 2015 Elsevier B.V. All rights reserved