[en] Three types of dechanneling by defects are considered: obstruction, distortion and a combination of the two. Obstruction corresponds to the Sizmann figure (blocking of the channel); distortion means that the channel is curved; in certain cases the two phenomena are combines. This classification enables defects to be distinguished and studied by the type of dechanneling they generate

[en] Published in summary form only

[en] The diffusion constant of mobile defects is diminished by the presence of traps because the interaction lowers the jump frequencies in the neighborhood of traps. Using standard techniques of scattering theory for randomly disordered systems, an explicit expression is obtained for the dependence of the effective diffusion constant on the density of traps and the change of the jump frequencies. The results for simple microscopic models are compared to a phenomenological theory, and the significance of parameters like binding energy and trapping radius is discussed

No abstract available

No abstract available

[en] Whenever an anti-electron enters matter, its positive charge will drive it towards a site where a positive charge is missing, it means towards a site where atoms are absent. The anti-electron will end by annihilating itself with an electron but the time taken by the anti-electron to annihilate depends on the size of the site. The larger the size, the longer the anti-electron lifetime because the probability to find an electron is smaller. The measurement of the anti-electron lifetimes when they penetrate matter gives information on the presence of nano-scale holes and can be used to do a mapping of defects. One of the challenges to overcome is to get an anti-electron source intense enough to get a mapping in a time delay suitable to industrial applications. (A.C.)

No abstract available

[en] Deep levels associated with the main impurities such as Cr, O and other defects in semi-insulating GaAs (Cr doped, O doped and undoped) have been measured by thermally stimulated current(TSC) measurements. Deep level energies and capture cross sections are obtained through quasi-fermi level analysis, initial rise, various heating rate and peak shape methods. Samples were annealed at 400 degC, 500 degC, 600 degC, and 700 degC, and from the annealing effects on the deep levels, a possible origin of the deep levels observed in pure GaAs (Bridgeman and LEC) is discussed. (Author)

[en] The author calculates the distortion of the flux line near a defect and illustrates the existence of the threshold value for the pinning. (Auth.)

[en] The core structure of the dislocation in a bubble raft has been evaluated by using the improved P-N equation. The dislocation profile has been obtained explicitly for the bubble radius R=0.296, 0.592, 0.650, 0.888 mm. The results show that the core width of dislocation will increase rapidly when the bubble radius decreases, especially, this trend will become more significant as the radius is more smaller. Our calculated results agree well with the experimental data, and our method can be used to predict the core structure of the dislocation in a bubble raft where bubble-radius is given arbitrarily.