A Novel p-Type ZnCoxOy Thin Film Grown by Atomic Layer Deposition

Reported herein is the atomic layer deposition (ALD) of novel ternary ZnCoxOy films possessing p-type semiconducting behavior. The preparation comprises of optimized ZnO and Co3O4 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/ Co3O4 to 1/10, a spinel structured ZnCoxOy film was grown at 150 degrees 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 ZnCoxOy film is more stable than its p-type analog Co3O4 film; and (4) upon p-n diode fabrication, the ZnCoxOy 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.

Automated summary

This paper reports the atomic layer deposition (ALD) of novel ternary ZnCoxOy films with p-type semiconducting behavior. The study optimized the deposition of ZnO and Co3O4 using commercial precursors, resulting in a spinel structured ZnCoxOy film with smooth surface, good crystallinity, and high purity. As the concentration of Co element increased, the transmittance and bandgap of the material decreased. The ZnCoxOy film was found to be more stable than its p-type analog Co3O4 film, and it exhibited good rectification behaviors and low reverse leakage when used in p-n diode fabrication.