Study of vacancy defects in PbSe and Pb1-xSnxSe by positron annihilation

Abstract

Positron lifetime measurements have been performed to study vacancy defects in vapour-liquid-solid (VLS) grown PbSe and Pb1-xSnxSe (x = 0.07, 0.1, 0.3). Post-growth annealing under various vapour pressure conditions has been used to change the number of Pb vacancies, resulting in the determination of the specific positron trapping rate μPbv = (1.0±0.1)×1014 s-1. The sensitivity range of the positron annihilation method to the Pb vacancies was found to be 1017<[VPb]<1020cm-3. Positron lifetimes in perfect PbTe, PbSe and PbS crystals have been calculated. Moreover, we have predicted lifetimes of positrons trapped by vacancies. The calculated lifetimes in bulk and defects correspond well to the experimentally determined values.