Charge carrier transport mechanism in the CdS/CdTe heterojunction with a zinc oxide front contact of a ZnO:Al/i-ZnO/CdS/CdTe/Cu/Ni structure has been investigated in the temperature range of 100-373 K. It has been found that at forward biases the charge carrier transport mechanism is determined by tunneling through charge states related to dislocations. An estimation of the concentration of dislocations gives a value of 2.9.10(2) cm(-2). At reverse biases higher than 0.7 V, the charge transport mechanism is determined by tunneling processes. The leakage current component is predominant for reverse voltages lower than 0.4 V. (C) 2012 Published by Elsevier B.V.