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The F control of the point defect density in preamorphized Si layers is studied by investigating the F incorporation process during the solid phase epitaxy (SPE) of amorphous Si layers. The results have demonstrated F to be a versatile and powerful tool to control the point defect density in Si, acting as a trap for the Is and indirectly modifying the diffusivity of dopants.

A scanning capacitance microscopy (SCM) was carried out in the angle beveling configuration on B doped, very narrow quantum wells (QWs) of Si0.75Ge0.25 layers strained between Si films. The results showed that a spatial SCM resolution of at least 5 nm was demonstrated on angle beveled samples, not only in terms of signal sensitivity, but also in terms of quantitative majority carrier profiling.

O:Er concentration effects on structural, electrical and optical properties of Si:Er:O layers are examined.

The article presents a complete analysis of the double sign anomaly of the Hall coefficient in the hydrogenated amorphous silicon (Si), which is usually formed by the plasma enhanced chemical vapor deposition technique. The various effects of the hydrogen content on the discussed anomaly are also studied.

A systematic study of the photon absorption in Si quantum dots (QDs) embedded in Si[O.sub.2] is carried out by varying several parameters of the QD synthesis. The data obtained for the material which showed an increase in the optical bandgap due to the amorphous-crystalline transition of the Si QDs could be used to better implement Si QDs for future PV technologies.

The structural and electrical characterization of Ge sample implanted with gallium and annealed at several temperatures. A simple model is used for describing the results by considering the thermally activated Ga clustering.

Electrical activation and clustering of B implanted in crystalline Ge (c-Ge) are described. The thermal stability has shown that the B clustering, responsible of B inactivity, is characterized by high binding energies and higher thermal budgets are required to make them dissolve.

The formation and growth of nanovoids in a C-doped Si layer after [He.sup.+] implantation and thermal annealing are described. The studies have shown how localized strain in epitaxial films can be effectively used to drive nanovoid formation and evolution.

The localization of voids in thin [Si.sub.1-x][Ge.sub.x] layers after [He.sup.+] implantation and thermal annealing is described. The results have shown that the compressive strain in the [Si.sub.1-x][Ge.sub.] layers have induced the nucleation of small cavities and the growth of voids by a mechanism where vacancies are stabilized by He.

The solid phase epitaxy regrowth (SPER) of strained [Si.sub.0.83][Ge.sub.0.17]/Si heterostructures grown by molecular beam epitaxy (MBE) and amorphized by [Ge.sup.+] ion implantation is studied. It is shown that the introduction of dopants such as B and Sb has increased the SPER rate but has no effects on the final quality and structure of the regrown SiGe in the activation energy for SiGe SPER process.

Different experimental techniques are used for determining the lattice deformation induced by substitutional B in Si. The results have led to more accurate strain determination, which is in agreement with other ab initio theoretical calculations.

The formation of He ion implantation induced nanovoids in Si and its influence on the self-interstitial (Is) supersaturation, thus affecting the diffusion and electrical activation of implanted boron in crystalline silicon are described. The uniform nanovoid distribution has determined a peculiar B box like shape and the simulation of B diffusion has indicated that changes in the B profile are attributed to a local suppression of the interstitial supersaturation (S) caused by the presence of the nanovoids.