Hypothesis on the Influence of the Magnetic Behaviour of Hydrogen Doped Zinc Oxide during Its Plasma Sputtering Process

Ali Salimian,Hari Upadhyaya,Abul Hasnath,Arjang Aminishahsavarani

doi:10.3390/coatings11020222

Ali Salimian, Hari Upadhyaya + Show 2 more

Open Access

https://doi.org/10.3390/coatings11020222

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Journal: Coatings	Publication Date: Feb 13, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: London South Bank University

Abstract

We investigate the complexity of the reactive sputtering of highly conductive zinc oxide thin films in the presence of hydrogen at room temperature. We report on the importance of precise geometric positioning of the substrate with respect to the magnetron to achieve maximum conductivity. We examine the electrical properties of the deposited thins films based on their position on the substrate holder relative to the magnetron. By considering early reports by other researchers on the angular dependency of plasma parameters and the effect of hydrogen doping on electric and magnetic properties of hydrogen-doped zinc oxide, we propose a hypothesis on the possibility of such properties resulting in the observations presented in this report pending further tests to verify this hypothesis. Overall, in this report we present the guide by which highly conductive zinc oxide thin film coatings can be prepared via RF sputtering with hydrogen presence along with argon as the sputtering gas.

Highlights

Transparent conductive oxides (TCOs) are materials that show both transparency and conductivity, with applications in solar cells, optoelectronics, electroluminescent panels and various flat panel displays, as reported in various studies [1,2,3,4,5,6,7]
We recently reported on enhancing the electrical properties of indium zinc oxide (IZO) and zinc oxide (ZnO) systems by repeated exposure of the sputtering target to an argon/hydrogen mixture as the working gas [29]
We have identified interesting complexities associated with reactive hydrogen/argon sputtering of un-doped ZnO targets, which we believe are associated with the reported magnetic properties of hydrogenated ZnO particles, and this report outlines our observations

Summary

Introduction

Transparent conductive oxides (TCOs) are materials that show both transparency and conductivity, with applications in solar cells, optoelectronics, electroluminescent panels and various flat panel displays, as reported in various studies [1,2,3,4,5,6,7]. There are some experimental reports on electrical conductivity improvements achieved in the ZnO system with the addition of hydrogen with respect to TCO materials Such reports only exist at the research state, and no commercial TCO based on pure ZnO doped with hydrogen is present in the market to the best of our knowledge. The authors recently reported on implementing a novel approach through which the sputtering plasma can be given a unique fingerprint based on the colour of the plasma, which is identical to the method by which colour functions of a light source are expressed in a “x” and “y” coordinate system to define the unique colour of the light source [30] We applied this technique for monitoring the plasma during these experiments and attempted to explain our observation by evaluating the colour parameters of the plasma in association with the electrical properties of the ZnO thin films deposited via reactive hydrogen/argon sputtering

Experimental

Spectral Data Collection from the Plasma Emissions

Results and Discussion

Analysis of the Plasma Emissions

Conclusions