Defect Characterization of InAs Wafers using Positron Lifetime Spectroscopy

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±2×10 16 cm-3. Very heavily doped n-type samples exhibit a defect lifetime of 332–340 ps, characteristic of divacancies. 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. The formation of the divacancytype defects may be correlated with a discrepancy between the carrier concentration and the total dopant concentration.