Design, implementation, and characterization of an automated SILAR system: validation with ZnO thin film deposition

The control of thin film deposition is an important issue in a wide range of applications, ranging from optoelectronic devices to active components in energy storage technologies. In this sense, the successive ionic layer adsorption and reaction (SILAR) technique has gained increasing interest from the scientific community for its simplicity, efficiency, and versatility in depositing several types of thin film materials of great technological interest over a variety of substrates, with tunable properties depending on the deposition parameters. Regarding the limitations and problems induced by using the conventional manual SILAR process, we present the design and implementation of a new automatic low-cost SILAR system for further developing and improving thin film deposition quality and reproducibility while avoiding operator fatigue. Our designed system relies on a motorized mobile platform with 1.8 degrees of freedom equipped with a multiple substrate holder, a control board in order to regulate the horizontal and vertical axis speed, and finally, an improved graphical user interface for controlling and monitoring the main parameters such as displacement speed in x\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$x$$\end{document} and y\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$y$$\end{document} directions, growth cycles, immersion, and rise time for each beaker. More particularly, the present study aims to improve the system’s programming in order to allow the motor to reach its maximum speed at start-up, reduce the cycle time, make it more controllable, and overcome the problem of time delay between cycles. The performance of the system was assessed by depositing crystalline zinc oxide (ZnO) thin film. Scanning electron microscopy, X-ray diffraction, and ultraviolet/visible spectroscopy demonstrated a good correlation between the evolution of the number of deposition cycles with the crystallite/grain size and film thickness. Moreover, controlling the instrument allows obtaining thin films with good adhesion and homogeneity. All these advantages make this technology promising at the industrial scale.