Effects of substrate temperature on sprayed ZnO thin films optical and morphological properties in terms of Amlouk-Boubaker opto-thermal expansivity ψAB

In this study, ZnO thin films have been grown using spray pyrolysis technique on glass substrates under various substrate temperature (400, 420, 440, 460, 480 and 500 deg. C). The Precursors were Propan-2-ol C3H8O and zinc acetate zinc Zn(CH3CO2)2 in acidified medium (acetic acid CH3CO2H, pH = 5). XRD analyses yielded a strong (0 0 2) X-ray diffraction line for low substrate temperatures (400-420 deg. C). This c-axis preferential orientation was not observed for substrate temperature beyond 440 deg. C. Atomic Force Microscopy (AFM) analyses monitored clusters with variable shapes (pyramidal for high temperatures and rounded concentrated ones for temperatures below 440 deg. C). Finally, the optical measurements were carried out via transmittance T(λ) and reflectance R(λ) spectra inside 250-2500 nm domain. Thanks to optical measurements, the conjoint optical and thermal properties were deduced using the Amlouk-Boubaker opto-thermal expansively ψAB.