engleski

Influence of light impurities on dislocation-related deep levels in p-type silicon

We present a study of dislocation-related defects in p-type silicon single crystals grown by the float-zone (FZ), carbon free, and polycrystalline silicon, carbon rich and grown by edge-defined film-fed growth (EFG) method. Deep level transient spectroscopy (DLTS) was used to identify electrically active defects. We have observed a broad Ev+0.33 eV level in EFG silicon and the Ev+0.39 eV level in FZ silicon. In order to measure defect capture cross sections we examined the intensity of the DLTS signal and peak position as a function of filling-pulse duration. The traps, both in FZ and EFG silicon, exhibit the logarithmic capture kinetics, a feature typical for extended defects such as dislocations. However, complex kinetics on defects in EFG material suggests that dislocations are decorated with impurity clouds, affecting therefore its electrical activity. We have clear evidence that oxygen affects strongly its electrical activity, however, the situation is not quite clear for carbon effect. Furthermore, we examined effects of low temperature annealing and found that brief treatments already at lowest temperatures significantly affect the dislocation activity.

silicon; defects; deep level transient spectroscopy

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