International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 04 | April-2016 www.irjet.net p-ISSN: 2395-0072 © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 2525 GRAPHENE BASED TUNNEL FET Jaya Verma Centre for Nanotechnology Research Vellore Institute of Technology,Vellore Taminadu-632007,India Abstract -In this paper, Graphene Based Tunnel Field Effect Transistor is presented. Graphene based tunnel field effect transistor mainly based on quantum tunneling from a graphene electrode through a thin insulating barrier. Graphenes are mainly used for grow film on substrate having much lower thermal coefficient. For preparing this hexagonal boron nitrite are used with oxidized Si wafer (300 nm of SiO2) and DRY transfer procedure are used to obtain monolayer graphene on to hbN crystal (20-25 nm thick) and this graphene layer reports for Dirac point . For tunneling of the device considered 1 to 30 hbN layers and doping concentration for encapsulated graphenes are approximately 0 and 10 11 that describes current-voltage characteristics over a wide range of operating conditions and provides viable route for high speed graphene tunnel field effect transistor with higher stability. The lack of an OFF state has been the main obstacle to the application of graphene based transistors in digital circuits. Recently vertical graphene tunnel field effect transistors with a low OFF state current have been reported; however, they exhibited a relatively weak effect of gate voltage on channel conductivity. Key Words:Graphene,Tunnel Field Effect Transistor,Gate Voltage 1.Introduction Graphene is highly transmittance material around 97.7% with high current density(10 8 amp /cm 2 ) . This material is most stronger than steel having 1100 GPa modulus and have atwo dimension honey combed structure of allotrope Carbon.Bare graphene is a semimetal with a zero band gap and shows performance of sp 2 hybridized material as shown in fig-1. A graphene based tunnel FET possess unique high frequency properties due to their high carrier mobility. Application of these FETs in digital circuits is, however, impossible due to the low ratio of ON to OFF state currents 1-4 . Fig -1:Graphene structure The vertical construction represented two parallel graphene sheets (source and drain) separated by a thin tunnel transparent dielectric layer of boron nitride. Both the barrier height and electron density in the contacts were controlled by the bottom gate. The measured characteristics showed that the influence of the gate voltage on the channel conductivity was weak (non- exponential) and the ON/OFF ratio reached only 50.The dependence of the current on the gate voltage in the proposed device is exponential with an inverse sub threshold slope reaching (60 mV/dec) –1 at room temperature. Considering the current–voltage characteristics of the device we take into account simultaneously both tunnel and thermionic current and show that the inverse sub threshold slope of the proposed FET (as well as of any schottky barrier FET) is limited to (60 mV/dec) –1 .The performance of graphene-based tunnel field effect transistors has been hampered by graphene’smetallic conductivity at the neutrality point (NP) and the unimpeded electron transport through potential barriers due to Klein tunneling, which limit the achievable ON-OFF switching ratios to ~10 3 and those achieved so far at room temperature to less than 10. These low ratios are sufficient for individual high-frequency transistors and analogue electronics but they present a fundamental problemfor any realistic prospect of graphene-based integrated circuits. A possible solution is to open a band gap in graphene, for example by using bilayer graphene , nanoribbons ,quantum dots or chemical