Fabrication of Transparent Very Thin SiOx Doped Diamond-Like Carbon Films on a Glass Substrate

Ya Chang,Hung Wei,Hung Chen,Wei Liao,Yan Liao,Chien Kuo

doi:10.3390/coatings8070240

Ya Chang, Hung Wei + Show 4 more

Open Access

https://doi.org/10.3390/coatings8070240

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Abstract

A novel direct current (DC) magnetron sputtering system via radio frequency (RF) bias with hexamethyldisiloxane (HMDSO) plasma polymerization was developed for the deposition of SiOx-doped diamond-like carbon (DLC) films on a glass substrate. As the RF bias increased, the ratio of intensity of D peak and G peak (I(D)/I(G)) decreased and the G peak shifted to a low position, leading to high hardness and a large portion of sp3 bonds. Additionally, weak sp2 graphite bonds were broken and sp3 diamond bonds formed because the RF bias attracted hydrogen ion bombarding the DLC films. Increasing DC power was helpful to improve the hardness of the DLC films because the proportion of sp3 bonds and the I(D)/I(G) ration was increased. HMDSO was introduced into this process to form SiOx:DLC films with enhanced optical performance. The average transmittance in the visible region of these very thin SiOx:DLC films with a thickness of 37.5 nm was 80.3% and the hardness of the SiOx:DLC films was increased to 7.4 GPa, which was 23.3% higher than that of B270 substrates.

Highlights

Diamond-like carbon (DLC) films are various forms of amorphous carbon materials with some of the unique properties of natural diamond [1,2]
An Ag concentration of 12.5 at.% yielded an optical band gap of 1.95 eV and reduced the transmittance [33]. These authors subsequently reported on the optical properties of fluorine-doped diamond-like carbon (DLC) thin films that were synthesized by plasma-enhanced chemical vapor deposition (PECVD) on glass and silicon substrates at visible and near-infrared wavelengths [34]
These results showed obtained by deposition using a direct current (DC) power of 50 W, were 10.1 GPa and 155 nm, respectively

Summary

Introduction

Diamond-like carbon (DLC) films are various forms of amorphous carbon materials with some of the unique properties of natural diamond [1,2]. Zhao et al prepared Ti-doped hydrogenated DLC films on polished stainless steel substrates and Si wafers in a radio frequency (RF) plasma-enhanced chemical vapor deposition (PECVD) and unbalanced magnetron sputtering system with an ultra-low friction coefficient of ~0.008 [26]. An Ag concentration of 12.5 at.% yielded an optical band gap of 1.95 eV and reduced the transmittance [33] These authors subsequently reported on the optical properties of fluorine-doped DLC thin films that were synthesized by PECVD on glass and silicon substrates at visible and near-infrared wavelengths [34]. Even though these studies involved DLC films on glass, their thickness always exceeded 170 nm, and sometimes even exceeded 2.9 μm. The transmittance in the visible region was improved by increasing the HMDSO flow rate, and the deposition thickness was controlled from 9.8 to 87.2 nm

Deposition of Transparent Very Thin Films

Measurements

Discussion

The wavenumber theGthe

The Transparent Very Thin SiOx:DLC Films

Conclusions