Abstract:
The compensation effect has been revealed in undoped polycrystalline CdTe synthesized during rapid crystallization. The revealed effect leads to an increase in the electrical resistivity to 10$^8$–10$^{10}$$\Omega$$\cdot$ cm at a background impurity concentration of
$\sim$10$^{15}$ cm$^{-3}$ (Ga$_{\mathrm{Cd}}$ and Cl$_{\mathrm{Te}}$ donors, unidentified acceptors). For some samples, this effect is accompanied by the appearance of persistent photoconductivity, which disappears at a temperature of $\sim$200 K. It has been shown that all the polycrystals studied are characterized by a three-level compensation mechanism in which the fundamental properties of the material are determined by deep donors and/or acceptors with a concentration of 10$^{12}$ cm$^{-3}$. Depending on the specific growth conditions, the electrical resistivity at room temperature is determined by deep centers with activation energies of 0.59 $\pm$ 0.10 and 0.71 $\pm$ 0.10 eV, which are supposedly related to intrinsic point defects, and deep centers with activation energies of 0.4 $\pm$ 0.1 eV, which belong to the DX center formed by the Ga$_{\mathrm{Cd}}$ donor.
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