Study on temperature dependent resistivity of indium-doped cadmium zinc telluride

Indium-doped CdZnTe crystals, grown by the modified vertical Bridgman method, were characterized by temperature dependent resistivity measurements in the range from 220 to 320 K. The Fermi level, pinned near the midgap, was confirmed by fitting ln(ρ) versus 1/k₀T plots, giving energies of 0.63 eV and 0.72 eV above the valence band for the high resistivity samples, with doping levels of 5.0 × 10¹⁶ at cm^-3 and 4.8 × 10¹⁷ at cm^-3, respectively. Different dominant deep level defects or complexes for pinning the Fermi level, and hence producing high resistivity, were expected when comparing the charge transport behaviours of the materials and the dopant concentration. However, two energies of 0.24 eV and 0.33 eV, below the conduction band for the Fermi level, were calculated at positive and negative bias voltages, respectively, for a low resistivity sample doped by 9.7 × 10¹⁷ at cm^-3 In.