Properties of Germanium Doped with Cobalt

Abstract

Measurements of the temperature dependence of electrical resistivity in $n$- and $p$-type cobalt-doped germanium crystals indicate that cobalt introduces acceptor levels in germanium at 0.31±0.01 ev from the conduction band and 0.25±0.01 ev from the valence band. Ionization energies deduced from infrared photoconductivity studies at 77°K are in good agreement with the values obtained from resistivity measurements. $N$-type samples show higher intrinsic photosensitivity than $p$-type samples and demonstrate quenching effects.