ELECTRON-BEAM-INDUCED CURRENT INVESTIGATIONS OF TRANSITION-METAL IMPURITIES AT EXTENDED DEFECTS IN SILICON

The electron beam induced current (EBIC) mode of a scanning electron m icroscopy is a useful technique for studying gettering of impurities t o extended defects, its high sensitivity allowing very low impurity co ncentrations to be studied. Extended defects, when studied by EBIC, no rmally exhibit one of two different kinds of carrier recombination beh avior. In the most common case this is accurately described by the Wil shaw model in which the recombination mechanism is charge controlled. Analyzed in terms of this physical model, quantitative EBIC experiment s indicate that the small amount of recombination associated with defo rmation induced dislocations produced at 650 degrees C or above and at stacking faults is due only to residual impurities, whereas a state i ntrinsic to the dislocation is produced by deformation at 420 degrees C. There also exists a less common second type of recombination behavi or, often associated with nickel contaminates, which can dominate at l ow temperatures. This type of recombination is less well understood an d cannot be modeled by simple Shockley Read Hall recombination statist ics.