Electrical properties of zinc oxide - Tetracene heterostructures with different n-type ZnO films

Electrical properties of organic-inorganic p-n heterojunction structures with tetracene (Tc) and zinc oxide (ZnO) films were investigated. The ZnO films had different n-type carrier concentrations that varied from similar to 10(15) cm(-3) to 10(19) cm(-3). Lower n-type ZnO layers resulted in decreased reverse currents in the ZnO:Al/ZnO/Tc/Au structures and in an improvement of their asymmetric properties. Experimentally determined energy level alignments at the ZnO/Tc interfaces were related to the electrical behavior of the structures. An improved rectification was associated with decreased generation-recombination currents at the ZnO/Tc interface due to an increased organic-inorganic interface energy gap. Current-voltage characteristics were analyzed by a differential approach. Electrical conduction mechanisms including bimolecular recombination as well as trap-filled limited conduction were identified in the investigated structures. (C) 2017 Elsevier B.V. All rights reserved.