Laser direct writing of graphene patterns
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Laser direct writing of graphene patterns J.B. Park, W. Xiong, Z.Q. Xie, M. Mitchell, Y. Gao, M. Qian, Y.F. Lu Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0511 ABSTRACT Rapid growth of single-layer graphene using laser-induced chemical vapor deposition (LCVD) with a visible CW laser (λ = 532 nm) irradiation at room temperature was investigated. In this study, an optically-pumped solid-state laser with a wavelength of 532 nm irradiates a thin nickel foil to induce a local temperature rise, thereby allowing the direct writing of graphene patterns about ~10 μm in width with high growth rate on precisely controlled positions. It is demonstrated that the fabrication of graphene patterns can be achieved with a single scan for each graphene pattern using LCVD with no annealing or preprocessing of the substrate. The scan speed reaches to about ~50 um/s, which indicates that the graphene pattern with 1:1 aspect ratio (x:y) can be grown in 0.2 sec. The patterned graphene on nickel was transferred to SiO2/Si substrate for fabrication of electrical circuits and sensor devices. INTRODUCTION Graphene is a really promising material in emerging electronic technology due to their outstanding electrical [1], mechanical [2,3], thermal [4], and optical properties [5]. 2-dimentional sheet can be used with current semiconductor manufacturing processes. Graphene will be the core material for flexible and transparent electronics [6], including displays, solar cells, sensors, and electrodes. Currently, graphene can be obtained through several different approaches such as mechanical exfoliation [7,8], annealing of SiC [9,10], and chemical vapor deposition (CVD) [11-14]. CVD is the most promising method due to the benefits of large-scale production of high quality graphene and transfer the graphene to arbitrary substrates for various applications [11]. Especially, large-scale patterns can be achieved by patterning of catalytic metal films before growth [12] or direct patterning of graphene after growth [13]. Although the CVD method can achieve large production volume using a roll-to-roll method [14], the fabrication of graphene patterns by CVD methods is a multi-step process which is time-consuming and costly. Generally, CVD methods consist of several steps including annealing, growth, cooling, and patterning process for fabrication graphene patterns, and the growth process needs several minutes up to a few hours [11-14]. Besides, the patterning process also requires expensive masks and time consuming processes. Therefore, more efforts are needed to make the conventional CVD techniques more suitable for electronic applications. In this study, we developed a direct writing method for fabrication of graphene patterns by laser-induced chemical vapor deposition (LCVD). Line patterns were fabricated on a nickel foil. Localized laser heating on the nickel foil resulted in a rapid local temperature rise at the laser focal point. The growth rate is three orders of magnitude faster than that of the general
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