Low-Temperature Large-Area Zinc Oxide Coating Prepared by Atmospheric Microplasma-Assisted Ultrasonic Spray Pyrolysis

Shih-Chen Shi,Po-Wei Huang,Jason Hsiao-Chun Yang

doi:10.3390/coatings11081001

Shih-Chen Shi, Po-Wei Huang + Show 1 more

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https://doi.org/10.3390/coatings11081001

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Journal: Coatings	Publication Date: Aug 22, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: National Cheng Kung University, Feng Chia University

Abstract

Zinc oxide (ZnO) coatings have various unique properties and are often used in applications such as transparent conductive films in photovoltaic systems. This study developed an atmospheric-pressure microplasma-enhanced ultrasonic spray pyrolysis system, which can prepare large-area ZnO coatings at low temperatures under atmospheric-pressure conditions. The addition of an atmospheric-pressure microplasma-assisted process helped improve the preparation of ZnO coatings under atmospheric conditions, compared to using a conventional ultrasonic spray pyrolysis process, effectively reducing the preparation temperature to 350 °C. A program-controlled three-axis platform demonstrated its potential for the large-scale synthesis of ZnO coatings. The X-ray diffraction results showed that the ZnO coatings prepared by ultrasonic spray pyrolysis exhibited (002) preferred growth orientation and had a visible-light penetration rate of more than 80%. After vacuum treatment, the ZnO reached a 1.0 × 10−3 Ωcm resistivity and a transmittance of 82%. The tribology behavior of ZnO showed that the vacuum-annealed coating had a low degree of wear and a low coefficient of friction as the uniformly distributed and dense coating increased its load capacity.

Highlights

Zinc oxide (ZnO) is a direct bandgap semiconductor material in the II–VI family of semiconductor compounds
ZnO is widely used in various applications, such as plasmonic metamaterials [1], laser materials [2], ultraviolet light sources [3], solar cell counter-electrodes [4], and transparent conducting oxides (TCOs) [5,6]
Badeker used a sputtering method to prepare cadmium oxide (CdO) [7], while Rupprecht discovered that indium (In) could be vacuum evaporated on a quartz plate

Summary

Introduction

Zinc oxide (ZnO) is a direct bandgap semiconductor material in the II–VI family of semiconductor compounds. It has a low free-radical excitation binding energy, a high melting point, good thermal conductivity, superior semiconducting characteristics, piezoelectric behavior, and photoconductive properties. ZnO is widely used in various applications, such as plasmonic metamaterials [1], laser materials [2], ultraviolet light sources [3], solar cell counter-electrodes [4], and transparent conducting oxides (TCOs) [5,6]. To increase the conductivity of semiconductor materials, compounds such as indium-doped tin oxide (ITO)—that is, using n-type doping—and aluminum-doped zinc oxide (AZO) and gallium-doped zinc oxide (GZO), using p-type doping were developed [10,11,12]

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