Development of Spark-Discharge System for Deposition of Metal Oxide Nanoparticles Having Uniform Distribution on Small Surface

Abstract

In the classical spark system, the fact that the distance between the electrodes is controlled separately with two separate micrometers can prevent the nanoparticles from properly coating the substrate surface. Therefore, in the present work, the classical system has been modified to eliminate this drawback. No study has been found in the literature with the simultaneous control of the distance between the electrodes. A microcontroller and electromechanical system were used in this modified spark discharge system. A shaft that has right and left teeth on it is driven by a microcontroller and moved by a stepper motor, providing simultaneous and equal control of the distance between the electrodes. In addition, with a second stepper motor, the circular movement of the substrate allowed the nanoparticles to accumulate around a center. The modified spark discharge system tested for undoped ZnO and Al-doped ZnO nanoparticles was synthesized with the Zn and Al metal electrode pairs such as Zn–Zn, Zn–Al, and Al–Al. The properties of thin films composed of nanoparticles were further studied by scanning electron microscopy, X-ray diffraction, and optical transmittance measurement. Based on the scanning electron microscopy analysis, it was observed that nanoparticles with smaller radii were obtained in a circular area in the center of the substrate, and these nanoparticles covered the substrate surface more smoothly and homogeneously. The average nanoparticle diameters for Zn–Zn electrodes were calculated as 94 nm and 42 nm for the classical spark discharge system and the modified spark discharge system, respectively. When Al–Zn electrodes were used, it was observed that the average size of the nanoparticles was 57 nm and that they were distributed very smoothly and homogeneously on the substrate surface. In addition, a decrease in optical transmittance values was observed due to decreasing mean radius values and uniformly dispersed nanoparticles.