Tuning the Electrical Properties of Tungsten Oxide Thin Films Deposited by Reactive Magnetron Sputtering

Tungsten oxide films are deposited onto glass and silicon substrates using reactive magnetron sputtering. Several studies have revealed difficulties in studying the electrical properties of resistive WOx films. The main objective of this work is to propose the capacitance meter as a method for study...

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Bibliographic Details
Published in:Coatings (Basel) 2022-02, Vol.12 (2), p.274
Main Authors: N’Djoré, Kouamé Boko Joël-Igor, Grafouté, Moussa, Makoudi, Younes, Hourani, Waël, Rousselot, Christophe
Format: Article
Language:English
Subjects:
Capacitance
Chemical composition
Chemical properties
Density distribution
Deposition
Electric potential
Electrical properties
Engineering Sciences
Evolution
Flow velocity
Glass substrates
Humidity
Ion density (concentration)
Magnetic properties
Magnetron sputtering
Materials
Metal oxide semiconductors
Oxide coatings
Oxygen
Sensors
Silicon substrates
Stoichiometry
Thin films
Tungsten oxides
Voltage
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Summary:Tungsten oxide films are deposited onto glass and silicon substrates using reactive magnetron sputtering. Several studies have revealed difficulties in studying the electrical properties of resistive WOx films. The main objective of this work is to propose the capacitance meter as a method for studying the electrical properties of resistive WOx films. In addition, we aim to establish the correlation between the deposition process and WOx physico-chemical properties. The study of the W-Ar-O2 system hysteresis permitted us to gather the films into four zones, which were delimited by different oxygen flow rate intervals. The identification of these zones was confirmed by the deposition rate, target voltage, chemical composition and electrical properties of the films. A gradual evolution of the capacitance-voltage curves of the metal-oxide-semiconductor structures, with the WOx thin films as the oxide layer, was globally observed with increasing oxygen flow rate. Ion density (Nss) and flat band voltage (Vfb) evolved inversely to oxygen flow rate. The relationship between the evolution of Nss and Vfb and the increase in oxygen flow rate reflects the improvement in oxygen stoichiometry in the WOx films. The WOx-Si interface trap density distribution (Dit) was also studied using the Terman method. It was observed that the films closest to stoichiometry, i.e., WO2 or WO3, showed the lowest values of Dit and Nss.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings12020274