Micro-Structural and Field Emission Characteristics of Nitrogen-Doped And Micro-Patterned Diamond-Like Carbon Films Prep
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Micro-Structural and Field Emission Characteristics of Nitrogen-Doped And MicroPatterned Diamond-Like Carbon Films Prepared by Pulsed Laser Deposition Ik Ho Shin, Jae Hyoung Choi, Jeong Yong Lee and Taek Dong Lee Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea ABSTRACT Effect of nitrogen doping on field emission characteristics of patterned Diamond-like Carbon (DLC) films was studied. The patterned DLC films were fabricated by the method reported previously[1]. Nitrogen-doping in DLC film was carried out by introducing N2 gas into the vacuum chamber during deposition. Higher emission current density of 0.3~0.4 mA/cm2 was observed for the films with 6 at % N than the undoped films but the emission current density decreased with further increase of N contents. Some changes in CN bonding characteristics with increasing N contents were observed. The CN bonding characteristics which seem to affect the electron emission properties of these films were studied by Raman spectroscopy, x-ray photoemission spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The electrical resistivity and the optical band gap measurements showed consistence with the above analyses. High-resolution transmission electron microscopic (HRTEM) results also support the formation of graphite-like phase in 9 at % N-doped DLC film. INTRODUCTION DLC films are mechanically hard, chemically inert and of great interest as cold cathodes for field emission display. Because of low threshold field and high current density, electron field emission behaviors of DLC films have been widely investigated by many researchers.[2, 3] In the previous paper[1], improved field emission characteristics of pulse laser deposited DLC films by the micro-patterning were reported. To understand the change in structure and electronic properties of DLC films upon nitrogen incorporation, several attempts have been made which are not found beyond disputation. Most of the researchers report an increase of conductivity by adding nitrogen in the DLC films[4, 5]. However, the role of nitrogen in DLC films in increasing conductivity is not clearly resolved. D. Mckenzie et al. and V. Veerasamy et al. found that a highly sp3 bonded DLC films deposited by filtered cathodic vacuum arc can be doped controllably by nitrogen[6, 7]. Schwan et al. reported that nitrogen in DLC films leads to a graphitization of amorphous carbon when deposited with plasma enhanced chemical vapor deposition system[8]. In the present work, nitrogen-doped DLC films were obtained by the laser ablation system and effects of nitrogen doping on micro-structure and field emission characteristics of patterned DLC films with varying nitrogen content were studied. To analyze the effects of nitrogen on bonding characteristics of CN bonds, Raman spectra, XPS and FT-IR analyses were employed. Also effects of nitrogen on the electrical properties and the optical band gap were studied. These effects are discus
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