Assessing the combined effects of chemical and mechanical parameters on silar-grown nanostructured ZnO thin films
Authors:   1. Laboratory of Materials, Signals, Systems and Physical Modeling, Faculty of Science, University Ibn Zohr-Agadir, Morocco
2. Laboratory of Lasers in Life Sciences, Environment and Manufacturing, National Institute for Lasers, Plasma and Radiation Physic, BRAHIM YDIR , AMINE AJDOUR ,   Laboratory of Materials, Signals, Systems and Physical Modeling, Faculty of Science, University Ibn Zohr-Agadir, Morocco, MOUAD SOUMANE ,   Laboratory of Materials, Signals, Systems and Physical Modeling, Faculty of Science, University Ibn Zohr-Agadir, Morocco, SAMIA ACHOUCH ,   Conception and Systems Laboratory, Mohammed V University in Rabat, Rabat, Morocco, DRIS BEN HMAMOU ,   Laboratory of Materials, Signals, Systems and Physical Modeling, Faculty of Science, University Ibn Zohr-Agadir, Morocco, IULIA ANTOHE ,   1. Laboratory of Lasers in Life Sciences, Environment and Manufacturing, National Institute for
Lasers, Plasma and Radiation Physics, Atomistilor 409 Street, 077125 Magurele, Romania
2. Academy of Romanian Scientists (AOSR), Ilfov 3 Street, 050044 Buchare, GABRIEL SOCOL ,   Laboratory of Lasers in Life Sciences, Environment and Manufacturing, National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409 Street, 077125 Magurele, Romania, LUIZA-IZABELA TODERAŞCU ,   Laboratory of Lasers in Life Sciences, Environment and Manufacturing, National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409 Street, 077125 Magurele, Romania, MARCELA SOCOL ,   Laboratory of Optical Processes in Nanostructured Materials, National Institute of Materials Physics, Atomistilor 405A Street, 077125 Magurele, Romania
Published: November 2024

In the literature, a comprehensive assessment of the combined impacts
of chemical and mechanical parameters on the properties of thin films grown by SILAR
is missing. In this work, ZnO film formation is investigated under variable precursor
concentration, pH, withdrawal speed and number of cycles. Interestingly, the produced
ZnO films displayed remarkable aspect ratio and morphological variability, ranging
from the commonly obtained nanograins shape towards hexagonal nanorods, flower-
like rods and nanoneedles, which to our knowledge have not yet been achieved by using
single step SILAR process. More particularly, low concentration and intermediate pH
and withdrawal rates were favorable for nanorods formation. In addition, increasing the
withdrawal speed from 26 to 30 cm·min-1 resulted in a thinner film with improved rod
uniformity and reduced crystallite size. This is the first study on the impact of substrate
withdrawal speed on SILAR films. Among all studied parameters, the number of cycles
was particularly useful for tuning film thickness, while preserving its target shape. In
addition, the films grown under a higher number of cycles showed improved film
crystallinity and rod orientation with reduced dislocation density, microstrain and
bandgap energy. In our conditions, the most suitable combination of parameters required
for exhibiting optimized nanorod-shaped coating are: a concentration of 0.07 M, pH of
10.5, speed of 30 cm·min-1 and 40 cycles. In this case, XRD, XPS, Raman and FTIR
spectra displayed typical features of hexagonal Wurtzite structure of ZnO with no
impurities within the film surface, whereas AFM measured a thickness of 1.4 μm with
243 nm surface roughness.