On the characterization of individual defects in silicon by EBIC

EBIC recombination-contrast of defects is mainly caused by impurity atmospheres surrounding them. The contrasts for geometrically similar defects in samples having different diffusion lengths L > 100 μm are in proportion to the defect strengths .     

EBIC/TEM Studies on the Relation between Electrical Properties,Crystallographic Structure,and Interaction with Point Defects of Epitaxial Stacking Faults in Silicon

Only after annealing, EBIC investigations on epitaxial layer defects partly gave contrasts. More information on the crystallographic structure of these defects was obtained in subsequent HVEM investigations. Experimental results confirmed the supposition that only the decoration of the crystallographic defects with additional recombination centres (impurity atoms), and not existence of the defects themselves, results in a detectable EBIC contrast. The observed getter efficiency of the various defect types is discussed. This efficiency is growing with increasing lattice distortion.     

Edge misfit dislocations in the GeSi/Si(001) pair: Conditions and specific features of high-quantity generation

Dislocation structure of Ge_xSi_1?x films (x=0.4?0.8) grown by molecular-beam epitaxy on Si(001) substrates was studied by means of transmission electron microscopy. It was found that the density of edge MDs formed at the early stage of plastic strain relaxation in the films could exceed the density of 60° MDs. In our previous publications, a predominant mechanism underlying the early formation of edge misfit dislocations (MD) in Ge_xSi_1?x/Si films with x>0.4 was identified; this mechanism involves the following processes. A 60° glissile MD provokes nucleation of a complementary 60° MD gliding on a mirror-like tilted plane (111). A new edge MD forms as a result of interaction of the two complementary 60° MDs, and the length of the newly formed edge MD can then be increased following the motion of the “arms” of the complementary 60° MDs. Based on this scenario of the edge MD generation process, we have calculated the critical thickness of insertion of an edge MD into GeSi layers of different compositions using the force balance model. The obtained values were found to be more than twice lower than the similar values for 60° MDs. This result suggests that a promising strategy towards obtaining dislocation arrays dominated by 90° dislocations in MBE-grown Ge_xSi_1?x/Si films can be implemented through preliminary growth on the substrate of a thin, slightly relaxed buffer layer with 60° MDs present in this layer. The dislocated buffer layer, acting as a source of threading dislocations, promotes the strain relaxation in the main growing film through nucleation of edge MDs in the film/buffer interface. It was shown that in the presence of threading dislocations penetrating from the relaxed buffer into the film nucleation of edge MDs in the stressed film can be initiated even if the film thickness remains small in comparison with the critical thickness for insertion of 60° MDs. Examples of such unusual MD generation processes are found in the literature.     

Irradiation-induced changes in the local environment of Si and Al in LnSiAlON glasses as probed by Al and Si NMR

Two compounds have been studied: an oxide glass from the Y-Si-Al-O system and an oxynitride glass from the Y-Si-Al-O-N system, both bombarded with Sn-ions (975 MeV, fluences ranging from 10¹² to 2.7 × 10¹³ Sn/cm²). The changes in the environment of the silicon and the aluminium were investigated using NMR spectroscopy. Irradiation by Sn ions leads to a loss of nitrogen in the silicon and probably the aluminium environments. Part of the aluminium changes from a network former coordination to a network modifier coordination while the oxide silicate network exhibits a higher cross-linking due to an increase of the population of bridging oxygen. Part of the aluminium in five-fold coordination is formed at the expense of aluminium in six-fold coordination in the case of the oxynitride glass and the changes in the silicon environment occur at lower fluences than for the oxide glass.     

Heat capacity of Pd40Ni40P20 in the deeply undercooled liquid state determined by relaxation experiments in the glass transition region

An indirect method is presented which allows for the heat capacity determination of deeply undercooled melts at temperatures in the glass transition region, which are inaccessible to continuous calorimetric measurements. The method is based only on the unique relaxation behavior of glass-forming liquids in the transition region, and thus is generally applicable for vitreous systems. Here it is illustrated by measurements of the specific heat of deeply undercooled Pd₄₀Ni₄₀P₂₀, a metallic bulk-glass former, resulting in a considerable approach of the measurements towards the isentropic limit. Additionally, the consequent application of this method allowed for the determination of the dependence of the glass temperature on the cooling rate during vitrification, yielding a linear relation between the glass temperature and the logarithm of the cooling rate, as observed for several non-metallic glass-forming systems.     

A discussion about the structural model of “nuclear magnetic resonance studies of glasses in the system Na2OB2O3SiO2”

The structural model for the system Na₂OB₂O₃SiO₂ suggested by Yun, Feller and Bray is discussed. A different structural model is suggested in this paper the results of which are in better agreement with experiment.