Characterization of optical and electrical properties of CdTe:Yb co-doped with Ge

The defect structure of CdTe doped with Yb and co-doped with Ge was investigated by a set of optical (photoluminescence, absorption, photoconductivity), galvanomagnetic and thermoelectric methods. The results can be explained by a model, in which Yb acts as a deep donor with the energy level at EV+0.3 eV corresponding to the Yb2+/Yb3+ electronic transition. Introduction of Yb with concentration 1019 cm−3 in the melt results in a decrease of electrically and optically active acceptor defects in the as-grown crystals and causes a decrease of electrical resistivity of CdTe:Ge. A line at 1.585 eV related to an exciton bound to a complex of Yb and Cd vacancy was observed both in photoluminescence and photoconductivity spectra.