Interface energy barrier tailoring the morphological structure evolution from ZnO nano/micro rod arrays to microcrystalline thin films by Mn doping

Abstract

Hexagonal wurtzite crystal structure of pure and Mn doped ZnO nano/micro rod arrays (N/MRAs) thin films have been grown on ZnO nuclei layers by a cost effective chemical bath deposition (CBD). Atomic force microscopic (AFM) images clearly reiterate the growth timing of nanorods (NRs) and microrods (MRs) on seeded glass substrate under level of degree of supersaturation. The morphology of the ZnO is evolved from ZnO N/MRAs to microcrystalline structures like rods, spherulitic by interface energy barrier induced coarsening mechanism at 10% Mn doping. The preferentially oriented (0002) crystallographic plane in the undoped ZnO N/MRAs illustrate that the most of the ZnO are vertically standing on the seeded glass substrate. The stacking polar (0001) crystallographic plane in ZnO N/MRAs is suppressed by Mn doping lead to the preferential growth orientation along (100) symmetric direction at doping level 10%. The first-order high frequency E₂ mode from the hexagonal wurtzite MRs gradually experiences out-plane of unit of the coordinates with Mn doping level respectively which indicate the Mn exist in the MRs. Optical absorption and atomic crystal defects within the electronic structure of pure and Mn doped ZnO N/MRAs were then analyzed by using ultraviolet-visible (UV-vis) and fluorescence spectroscopic technique respectively. In this work, we investigated how substrate/solution interfacial chemistry can be utilized to tailoring a new morphological structure by doping process. This interesting result will offer a new route for developing future nano/microdevices.