Structural and optical characterization of ZnO and ZnO:Al films deposited by MOCVD on oriented and amorphous substrates

ZnO and ZnO:Al doped films were deposited by MOCVD of Zn(tta)2•tmeda precursor on different substrates. The deposited layers were characterised by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). Film structure is strongly dependant by substrate and deposition conditions. Substrate preferential orientation induces formation of hexagonal nanocrystal structure or nanorods having different orientation. On amorphous substrate 1-D nanorods formation is promoted by the ZnO doping or by the presence of catalyzing layers. Optical properties of these ZnO layers have been studied and correlated to film structure. Post deposition annealing was performed at different temperatures, times and ambient conditions to study film properties modification. A tetrapod like formation has been observed in such cases.