One of the main problems of CdTe material and sensors on its basis is instability of parameters which is mostly caused by a presence of various structural inhomogeneities. It results in deterioration of the detectors capabilities.

In this work we investigated the temporary evolution of samples dark conductivity after the electric field applying. It was examined both pure and chlorine doped CdTe with specific resistance in the range of 10⁴–10⁹ W×cm. All samples were in the form of rectangular parallelepipeds and 6´2´1 mm³ in dimensions. Gold or indium contacts were deposited onto their opposite large grains. The value of external electric field was in the range of 0–100 V/cm. Samples resistance values measured in a time interval of 1 sec by means of digital multimeter connected to personal computer.

All studied samples can be divided into two groups. None non-equilibrium processes were revealed for the first one. The relaxation of specific resistance after dynamic excitation for the second type of samples in most cases is well described by empirical relation r (t) = A×t^-0.7+r_¥ and saturates in a few minutes. Besides that, experimental r(t) curves of some of these samples contain peaks – maxima as well as minima. The presence of instability does not depend on polarity of the applied field or type of contacts. It is worth also to note that the change of photoresistance is also expressed by power law dependence when the samples under investigations were illuminated by above bandgap light.

It is clear that observed spatial and time instability of electric characteristics in some CdTe samples relates to the structural inhomogeneities presented in these crystals. Modulation of the applied fields by extended defects (twins, low angle boundaries, stacking faults, etc.) and by non-uniformity of doping impurity distribution causes the polarization processes and substantially influences both the dark conductivity and photoconductivity.

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