HYDROGEN EFFECT ON THE OPTICAL-ACTIVITY OF DISLOCATIONS IN SILICON INTRODUCED AT ROOM-TEMPERATURE

Dislocations were introduced into silicon crystals by mechanical scratching at room temperature. The optical property of such dislocations was investigated by means of cathodoluminescence. Neither deformation-induced luminescence nor the exciton luminescence was detected in the scratched region, showing that a high density of nonradiative recombination centers is induced on or around dislocations. Hydrogen plasma treatment of a scratched crystal led to the appearance of the so-called D1-D4 luminescence lines along the scratch. Deep-level transient spectroscopy revealed that deep traps were induced by scratching and diminished drastically due to subsequent hydrogen plasma treatment. Thus, it was concluded that hydrogen passivated nonradiative recombination centers but not the luminescence centers. The characteristics in spatial distribution of D1 and D2 lines and those of D3 and D4 lines showed that these two groups of luminescence lines were of different origins. Since the specimens used were thought to be free from metal contamination, the luminescence was not related to metallic impurities incorporated in the dislocation core. The nonradiative recombination centers induced by scratching were annihilated due to annealing at temperatures higher than 500 °C. The release of hydrogen from the nonradiative centers in a hydrogenated specimen did not take place before they were annihilated by annealing. © 1994 American Institute of Physics.