A Novel p-Type ZnCo(x)O(y) Thin Film Grown by Atomic Layer Deposition

Reported herein is the atomic layer deposition (ALD) of novel ternary ZnCo(x)O(y) films possessing p-type semiconducting behavior. The preparation comprises of optimized ZnO and Co(3)O(4) deposition in sub-cycles using the commercially available precursors cyclopentadienylcobalt dicarbonyl (CpCo(CO)(2)), diethylzinc (DEZ) and ozone (O(3)). A systematic exploration of the film’s microstructure, crystallinity, optical properties and electrical properties was conducted and revealed an association with Zn/Co stoichiometry. The noteworthy results include the following: (1) by adjusting the sub-cycle of ZnO/ Co(3)O(4) to 1/10, a spinel structured ZnCo(x)O(y) film was grown at 150 °C, with it exhibiting a smooth surface, good crystallinity and high purity; (2) the material transmittance and bandgap decreased as the Co element concentration increased; (3) the ZnCo(x)O(y) film is more stable than its p-type analog Co(3)O(4) film; and (4) upon p-n diode fabrication, the ZnCo(x)O(y) film demonstrated good rectification behaviors as well as very low and stable reverse leakage in forward and reverse-biased voltages, respectively. Its application in thin film transistors and flexible or transparent semiconductor devices is highly suggested.