Recombination-generation behaviour of decorated defects in silicon

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Abstract
Presents a study of the electrical properties of deep states in silicon containing oxidation-induced stacking faults and dislocations. In general the electrical activity of stacking faults is associated with the Frank partial dislocation bounding it rather than the extra plane of the fault itself. In addition, the deep states associated with the partials of very clean stacking faults are rather ineffective as either generation or recombination centres. The authors have studied the effect of annealing oxidation-induced stacking faults in nitrogen and of decorating them with silver. After low-level decoration the defect states increase in concentration and the electron binding energy changes, tending to move the states towards the middle of the gap (hence increasing their effectiveness as generation centres). This level of decoration is not detectable with present-day TEM techniques. However, if the level of decoration is increased further, precipitates can be observed (using TEM) but the concentration of deep states decreases as does their electron binding energy. During this precipitative phase the intensity of the photoluminescence D lines is also seen to decrease substantially. These factors have a very considerable significance in relation to the imaging of extended defects using techniques which rely on recombination-generation effects and imply that the visibility of such defects is crucially dependent on the level of decoration.