The applicability of the EBIC technique for studying the gettering of impurities to dislocations and other extended defects is discussed, including how quantitative values for the energy level position and concentration of the resulting electronic states can be determined when the Wilshaw model of recombination is obeyed. New experimental results from “clean” dislocations deformed at 900°C are presented along with evidence of the existence of a band of states at dislocations. In addition, EBIC measurements of nickel decorated dislocations show recombination behaviour that may be described in terms of a mixture of Wilshaw's recombination model and another type of mechanism. Finally, a new effect termed “electron beam induced activity” has been discovered, whereby the electron beam increases the electrical activity observed.

The experimental requirements for relating EBIC contrast measurements to the recombination strength of defects in non-ideal specimens is discussed. Three criteria are given which must be met for such an interpretation of measurements to be made. In the second part of the paper the mechanism for recombination at dislocations in silicon is described together with experimental results from clean and decorated dislocations. Details are given of those situations in which copper contamination does not increase dislocation activity. Finally work on decorated stacking faults in silicon is presented.

Results are presented from an investigation concerning the influence of oxidation induced stacking faults, their bounding partial dislocations, and mechanically induced surface pits on the precipitation behaviour of copper in silicon. Controlled amounts of copper are diffused into wafers containing such defect structures so that their effect on precipitation behaviour can be studied using TEM and preferential etching techniques. These studies indicate the relative efficiencies of the different defect types as centres for the precipitation of copper and also reveal the different precipitate structures which are produced.

No abstract

No abstract