Complex Research on Amorphous Vanadium Oxide Thin Films Deposited by Gas Impulse Magnetron Sputtering

Abstract

In this work, a complex examination of vanadium oxide thin films prepared by gas impulse magnetron sputtering with various Ar:O2 gas ratios of 2:1 ÷ 8:1 was conducted. X-ray diffraction revealed the amorphous nature of the prepared thin films, and scanning electron microscopy images showed that the thin films were crack-free and homogenous. Optical properties investigations revealed that a higher oxygen content in the Ar:O2 atmosphere during sputtering caused an increase in transparency. The sample prepared with the highest amount of oxygen in the gas mixture during deposition had 51.1% of the average transmission in the visible wavelength range. A decrease in oxygen caused deterioration in the thin film transparency with the lowest value equal to 21.8%. Electrical measurements showed that the prepared thin films had a semiconducting character with either electron or hole conduction type, depending on the sputtering gas composition. A small amount of oxygen in the gas mixture resulted in the deposition of p-type thin films, whereas an increase in the amount of oxygen caused a change to n-type electrical conduction. Resistivity decreased with increasing Ar:O2 ratio. The gas sensing response toward diluted hydrogen was investigated for all the VxOy thin films, but at low operating temperatures, only the p-type thin films exhibited a visible response.