Study of Defects in GeTe and (GeTe)$\text{}_{1-x}$(AgBiTe_2)_x Solid Solutions by Positrons

Positron lifetimes and Doppler broadening of the annihilation line measurements were performed to study the vacancy type defects in polycrystalline GeTe and (GeTe)$\text{}_{(1-x)}$(AgBiTe$\text{}_{2}$)$\text{}_{x}$ (x=0,0.03,0.05,0.1,0.15,0.2, and 1) solid solutions. The values of lifetimes obtained are explained as due to positron and positronium saturated trapping at vacancies and vacancy clusters. The interdependence between mean positron lifetime and hole concentration is discussed.