Vacancy clusters in plastically deformed semiconductors

Experimental investigations of plastically deformed elemental and III-V sem iconductors prove that a high number of vacancies and vacancy clusters are formed. The formation of point defects by the motion of jogged dislocations is analysed. Vacancies formed behind the jog are not stable as a simple ch ain of vacancies. Instead, they are transformed immediately to stable three -dimensional agglomerates. The stability of various vacancy clusters has be en investigated by means of density-functional calculations. The positron l ifetime in such clusters was calculated and compared to experimental result s. The association of open-volume defects with the dislocation can be deriv ed from positron lifetime measurements. The analysis in a positron-trapping model characterizes the dislocation as a combined defect. The undisturbed dislocation line is a precursor trap for the positron capture in a deep tra p related to the vacancies bound to the dislocation.