Native vacancy defects in $Zn1−x(Mn,Co)xGeAs2$ studied with positron annihilation spectroscopy

We have studied vacancy defects in chalcopyrite semimagnetic semiconducting mixed $Zn1−x(Mn,Co)xGeAs2$ bulk crystals with alloy composition $x$ varying between 0.052 to 0.182 using positron annihilation spectroscopy. We identified As vacancies, potentially complexed with the transition metal alloying elements, in all the studied samples, while no cation vacancy related defects were detected. The positron lifetimes for the bulk $ZnGeAs2$ lattice and neutral As vacancy were determined to be $τB=220–230ps$ and $τAs=300±10ps$⁠, respectively. Our results also show that the $p$-type conductivity in the samples is not due to cation vacancy related acceptor centers. The As vacancies were found to be present at such low concentrations that they cannot be responsible for the compensation of the $p$-type conductivity or the reduction of mobility in the $Zn1−x(Mn,Co)xGeAs2$ samples.