Tailoring the Surface Functionalities of Radio Frequency Magnetron-Sputtered ZnO Thin Films by Ar/NH₃ Gas Mixture Surface-Wave Plasmas

Abstract

The surface functionalization of radio frequency magnetron-sputtered zinc oxide (ZnO) thin films tailored by low-pressure Ar/NH mixture surface-wave plasmas (SWPs) is discussed based on the results of photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectrophotometric measurements. At an Ar/NH gas mixture ratio of 70%/30%, both the PL intensity of the near-band-edge emission and the XRD intensity of the ZnO(002) reflection peak were enhanced by about 5.5 and 8 times, respectively, compared to the values for the as-grown sample. Furthermore, the XPS and spectrophotometric analyses using the fluorescent dye showed that the amine group functionalization over the surface of the ZnO films reached their maximum values at the same gas ratio. From the results of optical emission spectroscopic and ion mass spectrometric measurements in the Ar/NH mixture SWPs, it is inferred that the nitrogen-containing reactive species, such as NH ( x = 1-4) ions and NH ( y = 1, 2) molecules in addition to H radicals might crucially interact with the defective ZnO surface lattices to repair the ZnO thin films from compressive to strain-free crystallized structures, enhance the PL intensity, and produce the amine group surface functionalization.

N-Doped TiO2 Photocatalyst Coatings Synthesized by a Cold Atmospheric Plasma

“…19 Truscott and co-workers 37 also reported that NH radicals played a crucial role in the deposition of nitrogen-doped diamond by microwave plasma-activated CVD. Recently, Ciolan and co-workers 38 investigated Ar/NH 3 gas mixture plasma processing onto the RF magnetron-sputtered defective ZnO thin films. They claimed that the concentration of NH in the plasma was maximum at a small amount of NH 3 gas, which is determined from the product of NH 3 concentration and electron density.…”

ZnO surface modification with maleic anhydride using plasma treatment

“…Second, it is controllable and reproducible, fast, and efficient even in moderate conditions, as it enables high energy levels, requires reasonable power, and maintains the sample close to room temperature, preventing the degradation of particles. [ 13,16–18 ]…”

“…[9][10][11] On the other hand, some works explore zinc oxide functionalization through the plasma technique. [12][13][14][15] Plasma functionalization is an alternative to the traditional chemical methods, with several advantages. First, it is attractive from an environmental perspective since it is a dry, contaminant-free process.…”

“…Second, it is controllable and reproducible, fast, and efficient even in moderate conditions, as it enables high energy levels, requires reasonable power, and maintains the sample close to room temperature, preventing the degradation of particles. [13,[16][17][18] Studies in the literature promote the functionalization of ZnO through plasmas using molecular gases. [12][13]15] Ciolan et al [12] discussed the effects of the gas mixture ratio of argon to ammonia during surface amination of ZnO nanoparticles.…”

“…[13,[16][17][18] Studies in the literature promote the functionalization of ZnO through plasmas using molecular gases. [12][13]15] Ciolan et al [12] discussed the effects of the gas mixture ratio of argon to ammonia during surface amination of ZnO nanoparticles. Argon facilitates the dissociation of ammonia and the production of ionic species, responsible for introducing amine groups.…”