Positron-annihilation study of vacancy defects in InAs

Positron lifetime measurements on InAs wafers have shown that the positron bulk lifetime in InAs is 246±2 ps. Most samples exhibit a defect lifetime of 287±6 ps, which is attributable to monovacancy-impurity complexes with a concentration of 7±2×1016 cm-3 . Very heavily doped n-type samples exhibit a defect lifetime of 332–340 ps. The defects in these samples have divacancy character, but change their configuration at low temperatures to a monovacancy-type defect. The concentration of these defects is also close to 1017 cm-3 . Both types of defects are stable for rapid thermal annealing up to 850 °C, and both defects are neutral. It is proposed that the formation of the divacancy-type defects may be correlated with a discrepancy between the carrier concentration and the total dopant concentration.