Employing cold atmospheric plasma (Ar, He) on Ag thin film and their influences on surface morphology and anti-bacterial activity of silver films for water treatment

Abstract

In this work to investigate the effects of using different gases in cold atmospheric plasma (CAP) on surface treatment of silver thin films (100, 120 nm film thickness) He and Ar were employed. Ag was sputtered on glass substrate and X-ray diffraction (XRD) as well as atomic force microscopy (AFM) for structural and morphological studies before and after plasma radiation was carried out. Surface treatment of Ag thin films by CAP increased surface roughness especially with Ar plasma, this rise of surface roughness of Ag thin film leads to make their surface hydrophilic which can be very important for antibacterial activity of Ag films in removal of Escherichia coli (E. coli) which was used as target bacterium. Argon plasma radiation was more effective than helium on both surface morphology and anti-bacterial property. XRD results showed that crystalline orientation of [111] peak of silver remains as preferred orientation, but the grain size did not change that much after plasma treatment. The crystalline size was calculated by Debye-Scherrer formula using peak [111] of Ag samples (as the most intense peak of silver).

Enhanced Quality of Wafer‐Scale MoS2 Films by a Capping Layer Annealing Process

“…This value slightly increases compared to 0.167 nm of the pristine film (Figure d). This roughness might result from the plasma surface treatment during the capping layer deposition or from enhanced atomic movement during the high‐temperature annealing process . Figure g shows a schematic of the MoO 2 film morphology variation with increasing direct annealing temperature.…”

Effects of different gas flow rates and non-perpendicular incidence angles of argon cold atmospheric-pressure plasma jet on silver thin film treatment

“…6 and 7, respectively. The surface roughness of the samples was found by calculating the root mean square (RMS) of AFM data and can be evaluated by the following formula [53]:…”

“…To avoid oxidation, carbonation or nitration of the Ag thin film surface with such molecular gases as O 2 , air and N 2 , in this work, argon (Ar) is used as the working gas. In addition, in our early work [53], Ar plasma offered an acceptable antibacterial activity for removal of E. coli due to remarkable increment in the surface roughness (RMS) of Ag thin film with thickness of 120 nm (about 9 nm) compared to He plasma. Surface modification by nonequilibrium plasmas at atmospheric pressure can be accomplished by using two different approaches, i.e., the "direct (touch mode)" and the "remote (non-touch mode)" approach [29,59].…”

“…Furthermore, Talukder et al [52] used oxygen, hydrogen, and nitrogen jet plasmas (molecular feed gases) to improve electrical and optical property of the zinc oxide thin films using different types of working gas (employing both separated and sequential oxygen, hydrogen, and nitrogen plasma treatment). In addition, in our early work, the influence of non-thermal plasma jet (He and Ar) was studied to improve the antibacterial activity, surface roughness, and hydrophilic property of Ag thin films [53].…”

“…Among the various operational parameters of an APPJ, the gas flow rate has undoubtedly a key role in the propagation of the plasma outside the source on the substrate and affects significantly the shape and length of plasma plume for surface processing. However, as we know, the other parameters such as duration of exposure time, type of working gas as well as nozzle distance to treated sample are the most factors which have been investigated [21,23,[52][53][54]. For instance, R. Zhou studied the effects of different working gases (N 2 , He, O 2 as well as air) and applied voltage on the photo-catalytic property of TiO 2 for inactivation of E. coli cells in aqueous media under various exposure times (0-5 min) using atmospheric-pressure microplasma array (29 microplasma jet units) [55].…”