Electrical and optical properties of n- and p-type CuInTe2

The electrical properties between 80 and 300 K and the optical absorption at room temperature of both n- and p-type CuInTe2 are studied. The n-type sample is obtained by annealing p-type CuInTe2 in the presence of indium for a prolonged period of time. The p-type samples are grown by programmed directional freezing technique with slight excess of indium in the stoichiometry. Two defect levels with ED = 58 meV and EA around 15 meV are identified from the analysis of the temperature dependence of the carrier concentration. The origin of these levels, consistent with the covalent bonding model, is attributed to InCu and VTe, respectively. From a theoretical fit to the experimental data, the density of states effective mass of the electrons is found to be m n ★ = 0.16me. The estimated values of the conduction and valence-band deformation potentials are in agreement with the general trend observed in other I–III–VI2 compounds. Using the model proposed for the band-gap shrinkage, the energy gap of n-type CuInTe2 in the dilute limit is calculated to be 1.026 eV.