Nitrogen effects on generation and velocity of dislocations in Czochralski-grown silicon

The dynamic properties of individual dislocations in nitrogen (N)-doped Czochralski-grown Si crystals with concentrations up to 6× 1015 cm-3 were investigated at temperatures of 650-950 °C using the etch pit technique and compared with such characteristics of N-free Si crystals. The velocity of dislocations in motion in N-doped crystals was revealed to be unaffected by N doping. It was found that the generation of dislocations from a surface scratch was suppressed in N-doped Si and that the critical stress for dislocation generation increased with N concentration, which is interpreted as being due to dislocation immobilization caused by impurity segregation. N doping is concluded to be effective in the promotion of precipitation of oxygen impurity resulting in immobilization of dislocations.