Investigation of the influence of gas-dynamic spraying parameters on the quality of thin films of transparent conductive oxides

Abstract

Transparent conductive oxides (TCO) are widely used in modern optoelectronics due to the unique combination of high electrical conductivity and optical transparency in the visible spectrum range. The spray pyrolysis method is one of the most promising technological processes for obtaining thin-film TCO coatings; however, the quality of the resulting films critically depends on the gas-dynamic spraying parameters. The paper investigates how the carrier gas velocity, spraying pressure, substrate temperature, and precursor concentration influence the morphology, crystal structure, and electrophysical properties of thin films of indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO). The study employed the methods of X-ray diffraction analysis, optical spectroscopy, and four-probe measurement of electrical conductivity. It has been established that the optimal carrier gas velocity is 2.5-3.0 l/min at a pressure of 0.15-0.20 MPa for obtaining ITO films with minimum resistance (8.2×10-4 Ohm·cm) and maximum transparency (88% in the visible range). Increasing the substrate temperature from 350°C to 450°C leads to improved film crystallinity and a 40% reduction in resistivity. The mathematical model of the process showed a correlation between the Reynolds number of the gas flow and film thickness uniformity. The obtained results demonstrate the critical importance of optimizing gas-dynamic parameters for obtaining TCO thin films. The developed mathematical model allows predicting film properties depending on technological parameters and can be used to optimize industrial processes for producing transparent electrodes for solar cells and displays.