Influence of point defects on electroconductivity of CdTe films obtained by CMBD method for the solar elements

CdTe films with different compositions were fabricated by a novel and low cost CMBD method under atmospheric pressure hydrogen flow. Cd and Te granules of 99.999% purity were used as precursors. The dark current-voltage characteristics and resistivity (obtained by Van der Paw method) of CdTe films with various compositions were measured. Analysis of the dark current-voltage characteristics of the films showed that all the samples have 'ohmicity' i.e. showed no rectification in the range of measured voltages. The resistivity of the films was found to be in the range ρ∼10⁴ - 10⁵ ohm · cm. Next, the temperature dependence of the conductivity of CdTe films were measured in the range temperature 77 - 300 K by the Van der Paw method. The activation energies of CdTe films were found from data of the temperature dependence. The activation energies for p-CdTe films were Δ E₁=E_V+0.5 eV, Δ E₂=E_V+0.49 eV, Δ E₃=E_V+0.12 eV, Δ E₄=E_V+0.11 eV. In agreement with the literature data, these values of activation energy in CdTe films correspond to the ionized vacancy of cadmium V^'_Cd or the interstitial atoms of tellurium Te_ⁱ. (authors)