Molecular dynamics simulation study on cross-type graphene resonator Oh Kuen Kwon a , Ho Jung Hwang b,⇑ , Jeong Won Kang c,⇑ a Department of Electronic Engineering, Semyung University, Jecheon 390-711, Republic of Korea b School of Electrical and Electronic Engineering, Chung-Ang University, Seoul 156-756, Republic of Korea c Department of Transportation System Engineering, Graduate School of Transportation, Korea National University of Transportation, Uiwang-si, Gyeonggi-do 437-763, Republic of Korea article info Article history: Received 18 June 2013 Received in revised form 21 September 2013 Accepted 23 September 2013 Available online 28 October 2013 Keywords: Graphene resonator Cross-type graphene Molecular dynamics abstract The resonators based on graphene nanoribbon have been of interest for a building block to develop elec- tro-mechanical devices on a nanometer scale. Here, we present resonator schematics based on a cross- type graphene and investigate its dynamic features via classical molecular dynamics simulations. This cross-type graphene-resonator can detect the tension and electrical variations in two-dimension. Our simulation results showed that the cross-type graphene-resonator exhibits great potential in the appli- cations to detect the polarization of the zigzag or armchair directions, because its oscillation dynamics are electromechanically coupled and its electronic states directionally depend on the edge structures by controlling the widths of the zigzag and the armchair edges. The deflective motions of the cross-type graphene-resonator under the driving forces were very similar to those of the graphene-nanoribbon resonator. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Since its discovery, graphene [1–4] has attracted a great deal of attention by its extraordinary electronic and mechanical properties [5–9]. Recent researches have led to the development of high-fre- quency top-down fabricated mechanical resonators based on graphene [5–7]. Nanoelectromechanical system (NEMS) resona- tors, which provide high frequency resolution and long energy storage time, play an important role in many fields of science and engineering [10]. Thus, recently graphene has come to be re- garded as the basic elements of NEMS devices due to their unique mechanical properties [5–7]. Atalaya et al. [11] showed the relationship between the out- of-plane deflection and the driving force and discussed the tunabil- ity of graphene oscillators by changing the dc bias. Graphene resonators have demonstrated the potential to be very sensitive detectors of mass, charge and chemicals while improving the qual- ity factor [5,6,12]. In order to better understand the potential of graphene-based electrically actuated and detected resonators [6] and the challenges in realizing strain-engineered graphene devices [13,14], the vibrational properties of these systems should be investigated. Computational simulation works have advanced this field and helped reveal the potential of graphene devices in future technologies [15–24]. Until now, the resonators based on graphene nanoribbon (GNR) have been intensively investigated [5–8,11]. However, graphene- based resonators with different structures such as ring-type or cross-type can be also considered. In this work, we consider a cross-type graphene (CTG)-resonator. We present simple fabrica- tion schematics of a CTG-resonator and analyze its dynamic features via classical molecular dynamics (MD) simulations. Our simulation results show that the CTG-resonator has a great poten- tial in the applications to detect the polarization of the zigzag or armchair directions. 2. Simulation methods Fig. 1 shows the simple schematics of the fabrication proce- dures for the CTG-resonator. The metal is deposited on insulator film and then the hole is formed by selective etching processes after the masking process. After that, the graphene is transferred on the bottom plate. Suspended graphene sheets are fabricated with a peeling process similar to that reported previously [5]. In our schematics, the graphene sheet can be mechanically exfoliated over predefined hole etched into a SiO 2 surface [5]. Then, a cross- type mask pattern is formed on the graphene by the process of fine lithography. Afterward, both graphene and metal in uncovered re- gions are removed by reactive ion etching processes, and finally, the CTG-resonator can be fabricated. The bottom can be used as a gate to drive the electrostatic force to the CTG-resonator. To investigate the dynamics of the CTG-resonator, we performed the MD simulations using MD methods from previous 0927-0256/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.commatsci.2013.09.053 ⇑ Corresponding authors. Tel.: +82 43 841 5340; fax: +82 43 841 5466. E-mail addresses: hjhwang@cau.ac.kr (H.J. Hwang), jwkang@ut.ac.kr (J.W. Kang). Computational Materials Science 82 (2014) 280–285 Contents lists available at ScienceDirect Computational Materials Science journal homepage: www.elsevier.com/locate/commatsci