Dielectric studies of Zn1−xMnxSe1−yTey epilayers

We report on the dielectric properties of Zn1−xMnxSe1−yTey (0.015<X<0.048, 0.003<Y<0.103) epilayers, investigated by capacitance (C) and dissipation factor (D) measurements in the temperature range 180–460 K and in the frequency range 20 Hz–100 kHz. A Debye relaxation behavior of the polarization has been observed, with the relaxation time decreasing very quickly with increasing temperature. We found that the activation energy decreases with increasing Mn concentration and Te concentration. In the capacitance measurements, this energy increases with decreasing test frequency. The deduced activation energy from capacitance is consistent with that of the dissipation factor. We suggest that carrier hopping among structural defects can be used to interpret our results. The change of the activation energy with Mn and Te concentration is explained in terms of the four-center model, in which if the number of Mn or Te atoms increases in the nearest-neighbor sites of the defect, it can have four possible configurations. The measured defect behavior reflects the overall average of all energy levels involved in the center, and the result is weighted by the relative concentrations.