Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Full Length Article Fabrication of DLC nanoparticle clusters by μ-wave oven based plasma reactor with acetylene diluted in air precursor Chupong Pakpum ⁎ , Kanokwan Kanchiang Program in Applied Physics, Faculty of Science, Maejo University, Chiang Mai 50290, Thailand ARTICLE INFO Keywords: Acetylene Microwave oven based plasma Nanocrystalline diamond Superhydrophobic Silicon ABSTRACT This work developed a microwave oven based plasma reactor operated under vacuum pressure. This microwave plasma deposition system used to deposit diamond-like carbon (DLC) thin film on silicon substrate. System is custom-made and economically provides a very inexpensive way to conduct film deposition experiments by using a household microwave oven as a microwave source to get plasma discharge. DLC thin films were suc- cessfully deposited on silicon substrates by pure acetylene (C 2 H 2 ) plasma. Plasma species composed of; CN, N 2 , CO, C 2, and H are presented revealed by Optical Emission Spectroscopy. Energy Dispersive X-ray analysis in- dicated that the deposited film composed of carbon atoms 46.25% and silicon atoms 53.75%. Raman analysis showed D-band, G-band and nanocrystalline diamond band with sp 3 -hybridization contained in the films in the range of 48.75–64.08% that composed of chemical bonding; CeC, C]O, C]N, CeN, CeO, CeNeH, NeO, OeH and HeOeH, analyzed by XPS technique. XRD indicated that the grown films are cubic diamond (1 1 1) crys- tallography and formed in coral-like clusters from nanoparticles of a mixture between sp 2 and sp 3 hybridization with high porosity in surface texture that introducing the hydrophobic property on the grown DLC surface by changing the hydrophilic property of smooth silicon substrate surface. 1. Introduction Plasma is considered as the fourth state of matter that consist of charged particles and neutral atoms. It has been used in laboratories as sources to provide desired ions, electrons, and neutral atoms depending on the applications. Plasma which exists in a vacuum circumstance can be created by various methods such as; direct current (DC) method by utilizing electric field produced between two electrodes to create plasma, radio frequency (RF) method by utilizing electric field pro- duced by RF driving voltage at electrode (or antenna) to induce elec- trons to oscillate back and forth at the same input frequency and re- sulting in ionization process consequently plasma generated (generally, the frequency used is at 450 kHz, 2 MHz, 4 MHz, 13.56 MHz and 27.12 MHz) and microwave frequency (MW) method by utilizing mi- crowave produced by magnetron that send out waveguide to oscillate electron at frequency 2.45 GHz to produce plasma as the same fashion with RF method does. Among the various methods, microwave plasma offers advantages, in that the plasma can be maintained in low-pressure plasma (267–800 Pa) and also provides a lower cost because the mag- netron tubes that produce microwave are used in household microwave ovens across the world that produce in production mass leading to economies of scale. Diamond-like carbon (DLC) is one of the many forms of carbon, its structure consists of sp 3 and sp 2 hybridized bonds in an amorphous carbon phase. DLC offers several excellent properties such as extremely high hardness, high density, low friction coefficient, chemical inertness, relatively high thermal conductivity and visual transparency [1]. DLC films are able to produce by microwave plasma under a wide range from low vacuum (pressure > 25 Torr (3333 Pa)) to medium vacuum (25 to 10 -3 Torr or 3333 to 0.133 Pa), such a pressure can be reached only by using the mechanical rotary vane pump, and produced struc- tures in the range variety of forms depending on processing parameters such as; operating pressure, type of precursor and operating power. S.A. Rakha et al. [2] produced one-dimensional CeC nanostructure of dia- mond-graphite nanorods on silicon by argon rich, Ar/N 2 /CH 4 mixtures, the microwave plasma chemical vapor deposition method at operating pressure 10,665 Pa, substrate temperature 850 °C and microwave power 1800 W. Hemawan et al. [3] deposited polycrystalline diamond films on silicon substrates at a substrate temperature of 950–1150 °C at high- pressure 23,998–31,997 Pa in high microwave power densities 150–475 W/cm 3 using 2–5% CH 4 /H 2 input gas chemistries and micro- wave input powers between 1.8 and 2.4 kW. Nanocrystalline diamond films were produced by Podgursky et al. [4], used microwave plasma enhanced chemical vapor deposition in CH 4 /H 2 /Air plasma at https://doi.org/10.1016/j.apsusc.2018.07.065 Received 20 May 2018; Received in revised form 1 July 2018; Accepted 10 July 2018 ⁎ Corresponding author. E-mail address: chupong@mju.ac.th (C. Pakpum). Applied Surface Science 458 (2018) 100–110 Available online 12 July 2018 0169-4332/ © 2018 Elsevier B.V. All rights reserved. T