Effects of Solution Precursor on Structural, Morphological, and Photoelectrochemical Properties of ZnO Layers Deposited by Recurrent Cyclic Voltammetry FOUDIL RAHAL 1,2 and DJAMILA ABDI 3,4 1.—Laboratoire d’e ´nerge ´tique et d’e ´lectrochimie du solide, De ´partement de chimie, Faculte ´ des Sciences, U.F.A., 19000 Se ´tif 1, Algeria. 2.—De ´partement de chimie, faculte ´ des sciences, Universite ´ Mouloud Mammeri, Tizi Ouzou, Algeria. 3.—Laboratoire d’e ´nerge ´tique et d’e ´lectrochimie du solide, De ´partement de ge ´nie des proce ´de ´s, Faculte ´ de Technologie, U.F.A., 19000 Se ´tif 1, Algeria. 4.—e-mail: naimadjam@hotmail.com The effects of the choice of the starting solution on the crystalline growth and structural and photoelectrochemical properties of zinc oxide films deposited on conductive (fluorine-doped tin oxide) glass substrate by cyclic voltammetry at 70°C have been studied. The morphology of the deposits was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photoelectrochemical response in K 2 SO 4 solution was followed by voltammetry and chronoamperometry. X-ray diffraction analysis revealed hexagonal wurtzite crystalline structure for all the films, with randomly oriented crys- tallites for the ZnO film prepared from zinc chloride or from an equimolar mixture of zinc chloride and zinc nitrate. Meanwhile, the films developed from zinc nitrate or from zinc acetate solution presented preferential (002) orien- tation. SEM revealed nanometric grains with hexagonal shape for all the films. The effects of the choice of the precursor on the symmetry, kurtosis, and roughness of the different films was evidenced by AFM, revealing that the roughness varied from 40 nm to 87 nm depending on the starting solution. The photoelectrochemical performance of the films was evaluated by chronoamperometry, revealing a strong anodic photocurrent and confirming their n-type semiconducting nature. Key words: ZnO, precursor solution, electrodeposition, voltammetry, photoactivity INTRODUCTION Over the last few years, zinc oxide (ZnO) thin films have been the subject of great development and considerable attention from the scientific com- munity. This is partly due to their good optical and electrical characteristics and their transparency at visible wavelengths. They present a large direct bandgap as n-type semiconductors, 1 resulting in growing interest in their use for numerous applica- tions. They are applied in many industrial and technical areas, e.g., photocatalysis, 2 photosensors, 3 piezoelectric transducers, 4 optoelectronic devices, 5,6 and emitting devices. 7 ZnO is also a potential candidate for negative temperature coefficient of resistance (NTCR)-based thermistor applications. 8 ZnO films are generally synthesized using several methods, such as sol–gel, 9,10 radiofrequency (RF) magnetron sputtering, 11,12 aqueous solution, 13 pulsed laser deposition, 14,15 spray pyrolysis, 16,17 chemical vapor deposition (CVD), 18 solution com- bustion synthesis (SCS), 19 ball milling, 20 and elec- trochemical deposition approaches, which offer various advantages in comparison with other pro- cedures. 21–25 The three oxygen precursors that are most widely used in electrodeposition are molecular (Received October 25, 2019; accepted April 29, 2020) Journal of ELECTRONIC MATERIALS https://doi.org/10.1007/s11664-020-08166-y Ó 2020 The Minerals, Metals & Materials Society