Effect of Solution Concentration on ZnO/ZnAl2O4 Nanocomposite Thin Films Formation Deposited by Ultrasonic Spray Pyrolysis on Glass and Si(111) Substrates
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2020-06-10
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Abstract
A complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si(111) substrates have
been successively obtained by a soft ultrasonic spray pyrolysis (USP) method deposition using the
Zn/Al molar ratios concentrations of 0.07/0.13 and 0.1/0.1, respectively. According to (XRD) an
ordered zinc oxide (ZnO) and zinc aluminate (ZnAl2O4) structures deposited onto glass from the air
annealing at 500 °C during 2 hours was observed and confirmed by the (EDX), (FTIR) and Raman
spectroscopy techniques. The estimated crystallites size and stress values of ZnO and ZnAl2O4 in the
ZnO/ZnAl2O4/glass film were 19 nm/0.469 GPa and 11 nm/-0.292 GPa, respectively. The lower
Zn/Al molar ratio around 0.035/0.06 produced only ZnO as a single phase, suggesting the Al
insufficient quantity. The Si(100) substrate with 0.07 Zn molarity conducted to the
Zn2SiO4/ZnO/ZnAl2O4 composite. The Raman integrated intensity bands of ZnO and ZnAl2O4
increases with increasing Zn to Al molar ratio (0.1/0.1 comparatively to 0.07/0.13). The
ZnO&ZnAl2O4 crystallinity enhances as Zn molarity increases. The ZnO films in the composites grow
with (002) texture. The TC(hkl) value indicated that ZnAl2O4 in the ZnO/ZnAl2O4/glass layer is
polycrystalline preferentially oriented along the (311) plane. Spinel ZnAl2O4 oxide onto Si(111)
substrate grown according to the (220) orientation. Crystallites are larger in ZnO/ZnAl2O4/Si than in
ZnO/ZnAl2O4/glass. The ZnO/ZnAl2O4 film onto glass substrate is transparent in the visible and near
infrared regions and sensitive to UV absorption, as characterized by UV-Vis spectroscopy. The ZnO
and ZnAl2O4 Eg values in the ZnO/ZnAl2O4/glass composite were 3.25 and 3.88 eV, respectively.