Impurity effects on the generation, velocity, and immobilization of dislocations in GaAs

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Abstract
The effects of various kinds of impurities, Al, In, Si, Te, and Zn, on the dynamic behavior of dislocations in GaAs crystals are investigated. The dislocation generation from a surface scratch is suppressed by the doping of the impurities. Generally, the suppression effect of any given kind of impurities depends on the type of dislocations to be generated. However, no systematic dependence on the size misfit or the electrical activity of the impurity atom is found in the suppression efficiency. The immobilization of originally fresh dislocations due to aging at elevated temperature is investigated. The results are interpreted to be due to the gettering of impurities by the dislocations. The feature of the suppression effect in dislocation generation is well correlated to that of the dislocation immobilization due to impurity gettering. It is concluded that the suppression of dislocation generation by impurity doping originates from dislocation immobilization due to impurity gettering. Isovalent impurities are found not to affect the velocities of dislocations of any type in motion. On the other hand, the effect of electrically active impurities on dislocation velocity depends on both the electrical property of the impurities and the type of dislocations in motion.