Digest Journal of Nanomaterials and Biostructures Vol. 7, No. 4, October-December 2012, p. 1787-1791 STUDY OF ELECTROSTATIC POTENTIAL SURFACE AROUND BIPYRAMIDAL GaAs QUANTUM DOT HANAFI ITHNIN, AHMAD RADZI MAT ISA, MOHD KHALID KASMIN , M. A.SAEED * Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia Semiconductor quantum dot have got scientific interest because of their unique electronic nature. In this article, an isolated square bipyramidal gallium arsenide (GaAs) quantum dot has been optimized using DFT method. The size of quantum dot was 1.2 nm 2 (square base) and 1.7nm height and consisted of total 84 atoms. The quantum dot was optimized using hybrid B3LYP functional and SBKJC pseudo potential basis sets. The electrostatic potential surface around the optimized GaAs quantum dot was plotted and the result showed the potential on the pyramid surface was polarized with two positive and negative surfaces. This potential was due electronic and nuclear charge of different arrangement on the surface structure of the dot. (Received February 20, 2012; Accepted November 10, 2012) 1. Introduction Electrostatic potential is associated with a charge distribution and can be defined as the potential energy of a test particle per unit charge of the particle. At molecular level, the electrostatic potential has been studied to determine the interaction of the molecule with its surrounding. The electrostatic potential study also explains the electronic distribution and structure formation of a molecule. Various studies about molecular electrostatic potential have been carried out to enlighten the behavior and interaction of the molecules to its environment. In chemical and biological field this phenomenon has been employed to studying the interaction of molecule such as protein, DNA and vaccine [1-5]. In physics it is mainly focused towards the electronic part such as the interaction of potential energy surface with charge particle and the development of nanodevices. Lis et.al have studied gated quantum dot to tune the confinement potential for nanodevices [6]. Whereas, the others groups measured the potential distribution around probe tip as instrument development [7-8]. The focus of the present study is to explore the role of electrostatic potential in Single Electron Transistor (SET), which is vital in SET development. The main phenomenon behind the working of SET is tunneling of electron. Many studies have been conducted to simulate the tunneling phenomena [9-12] and Boese et.al has concluded in their study that the electron tunneling through molecular nano-devices is inevitably controlled by its electronic and mechanical structure [13]. Due to quantum mechanical behaviour of tunneling, the interaction of the single electron tunneling to the quantum dot is still unclear. In this paper, the electrostatic potential surface around isolated GaAs bipyrimidal quantum dot is presented. This study will give an insight on behavior of the single electron interaction with the quantum dot during the tunneling to the quantum dot process. * Corresponding author: saeed@utm.my