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T2.8.1

Synthesis and Characterization of Nanocrystalline Diamond and Its Biomedical Application Zhenqing Xu1, 2, Arun Kumar2, Ashok Kumar1, 2, Arun Sikder2 1 Department of Mechanical Engineering, University of South Florida, Tampa, FL, 33620, USA 2 Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL, 33620, USA ABSTRACT Diamond is known as the material that has excellent mechanical, electrical and chemical properties. Diamond is also an ideal interface that is compatible with microelectronics process and biological environments to work as a biosensor platform with excellent selectivity and stability. In our study, nanocrystalline diamond (NCD) films were grown on Si substrates by the microwave plasma enhanced chemical vapor deposition (MPECVD) method. Parameters such as gas composition, temperature and pressure are investigated to get the best film quality. Scanning electron microscopy (SEM) and Raman spectroscopy were used to characterize the NCD films. Then the NCD films were treated by hydrogen plasma in the CVD chamber to obtain the hydrogen terminated surface. This hydrogenated NCD film is ready for bio-modification and can work as the platform of the biosensors. Fourier Transform Infrared Spectroscopy (FTIR) and Xray Photoelectron Spectroscopy (XPS) were employed to confirm the surface hydrogenation. INTRODUCTION In recent years, there has been much interest in the diamond films deposited using the chemical vapor deposition (CVD) technique due to the unique properties and potential applications in various areas. However, the synthesis of microcrystalline diamond films (MCD) results in large grain size and a very rough surface. Presently, the studies of nanocrystalline diamond films have been widely focused [1-4]. Compared with the microcrystalline diamond films, nanodiamond has a great deal of outstanding properties including a smooth surface, low coefficient of friction, ultrahigh nuclei density and negative electron affinity [5-7]. These properties show nanocrystalline diamond could be used in a wide range of applications including microelectrical mechanical systems, abrasive coatings, field emission electrodes and biosensors [8-10]. There are several methods to synthesize nanocrystalline diamond films. Gruen et al has demonstrated that NCD thin films can be deposited from Ar/H2/CH4 as reacting gas at different concentration of Ar. It was observed that the structures of the films changed from microcrystalline to nanocrystalline with the increase of Ar gas [11]. Other than using Ar, it has been reported that smooth NCD films were produced using a high methane concentration in a hydrogen environment [12]. Also, in order to avoid the surface damaging by the ex situ (scratching or ultrasonic) treatments, the NCD films are obtained directly on a mirror polished substrate using biased enhanced growth [2] by the MPECVD method. In this paper, nanocrystalline diamond films were deposited using an MPECVD system. In order to study the parameters’ effect during the synthesis, dif