Surface structurization and control of CuS particle size by discharge mode of inductively coupled plasma and vapor-phase sulfurization

Abstract

Copper sulfide (CuS) nanoparticle films with different nanoparticle sizes were fabricated using an inductively coupled plasma (ICP) and a vapor-phase sulfurization method. First, the ICP is applied to a thin copper film to obtain a copper nanoparticle film, based on the plasma-surface interactions through the ion bombardment on the film. The fabrication of the Cu nanoparticles revealed that their size and spatial distribution depend on the discharge mode of the ICP and plasma irradiation time. From the measurements of the plasma density, optical emission spectrum, and ion flux energy distribution function, it was found that the inductive mode of the ICP, compared to the capacitive mode of the ICP, is efficient at fabricating the uniform nanoparticle film due to the optimal plasma potential and high ion flux with narrow ion energy distribution. The Cu nanoparticles are then transformed to CuS nanoparticles through vaporphase sulfurization. For the hydrophobicity application of the CuS nanoparticle film, the contact angles of the CuS nanoparticle films were measured and compared with those of other thin films, such as SiO 2 and bulk CuS. The contact angle of the CuS nanoparticle film, fabricated through the plasma-surface interactions and sulfurization, was significantly higher than that of other thin films owing to the hydrophobic surface of the CuS with the nanoparticle structure.

Plasma-surface interactions

“…While plasma-surface interactions like secondary electron emission have a direct feedback effect on the plasma, other plasma-surface interactions lead to a modification of the surface itself. By bombarding a copper substrate with argon ions from a plasma, Daehan et al [14] produce copper nanoparticles with a specific size distribution by varying the plasma discharge conditions. Plasma charging of a substrate can also produce important effects, as demonstrated in the contribution by Bal et al [15] where electron charging of a catalyst can be used to control the catalyst activity for the improved activation of CO 2 .…”

Enhancing the Properties of Photocatalysts via Nonthermal Plasma Modification: Recent Advances, Treatment Variables, Mechanisms, and Perspectives

“…How et al reported a higher sputtered deposition under a higher working pressure using the same power. RF low-pressure inductively coupled plasma (ICP) was utilized to prepare Cu/CuS nanoparticle films under different power . It was revealed that the delivered power had a strong influence on the plasma density and the ion energy, which could change the surface structure of Cu with different nanoparticle sizes and spatial distributions.…”

“…98 The electron temperature and ion flux of plasma surface reactions were measured in realtime by the floating harmonic method under different power, bias power, and pressure. 99 Choi et al 86 also measured the plasma density and ion flux energy distribution function during the fabrication of Cu/CuS nanoparticle films utilizing a floating harmonic probe. It was found that the capacitive-(E)-toinductive-(H) mode transition happened with increasing applied power from 40 to 120 W. Meanwhile, in E and H mode (80 and 120 W, respectively), the size changes and spatial distribution of nanoparticles could be observed from the SEM images, which may connect with the ion flux energy distribution function and the energy that was transmitted to the Cu film.…”