1. Radiation Damage Quick Study Edward Cazalas 3/27/13

2. Goal What is damage? How is damage quantified? How much damage previously observed in graphene? Now what? Determine…

3. What is Damage? Damage are defects in graphene structure Concentrate on ion induced defects Displacement of carbon atom constitutes damage (~33 eV ejection energy) Removal of atom may be direct (with graphene) or indirect (backscatter from substrate, sputtering) Mono-vacancy (proton-carbon), di-vacancy (proton-bond) Kotakoski, J., Krasheninnikov, A.V., “Native and irradiation-induced defects in graphene: What can we learn from atomistic simulations?” University of Helsinki, May 28, 2010.

4. Mathew, S., et al., “The effect of layer number and substrate on the stability of graphene under MeV proton beam irradiation.” Carbon, Vol. 49, Issue 5, April 2011, pp 1720-1726. Pantelic, R., et al., “The application of graphene as a sample support in transmission electron microscopy.” Solid State Communications, Vol. 152, Issue 15, August 2002, pp 1375-1382. How is Damage Quantified? TEM (Tunneling electron microscope) 80 keV (300 keV ~10 7 e-/nm 2 inset) Raman Spectroscopy a)Single layer pristine suspended graphene b)1E18 ions/cm 2 c)1E19 ions/cm 2

5. Mathew, S., et al., “The effect of layer number and substrate on the stability of graphene under MeV proton beam irradiation.” Carbon, Vol. 49, Issue 5, April 2011, p 1720-1726. Previous Study - Proton Irradiation 2 MeV p+ Threshold at 1E16 ions/cm 2 1E17 ions/cm 2 1E18 ions/cm 2 6E18 ions/cm 2

6. Mathew, S., et al., “The effect of layer number and substrate on the stability of graphene under MeV proton beam irradiation.” Carbon, Vol. 49, Issue 5, April 2011, p 1720-1726. Previous Study - Proton Irradiation 2 MeV p+ 1E17 ions/cm 2 1E18 ions/cm 2 6E18 ions/cm 2 1E18 ions/cm 2 1E19 ions/cm 2 SupportedSuspended Electronically stimulated desorption – bond breaking Substrate allows additional modes of energy dissipation Coulombic interaction

7. Jung, N., et al., “Raman Enhancement of Graphene: Adsorbed and Intercalated Molecular Species”, American Chemical Society, Nano, Vol. 4, No. 11, 2010, pp 7005-7013. Cancado, L.G., et al., “Quantifying Defects in Graphene via Raman Spectroscopy at Different Excitation Energies.” American Chemical Society, Nano Letters, Vol. 11, 2011, pp 3190-3196. Neutron Damage Damage occurs through neutron-carbon ejection (elastic scattering) Carbon neutron σ ≈ 1b = 1E-24 cm 2 Graphene atomic surface density = 3.8E15/cm 2 Neutron Fluence = 1E16 n/cm 2 Carbon ejection surface density = 3.8E7/cm 2 n D (cm -2 ) = 7.3E9 E 4 (I D /I G )E = 2.2 eV for 562 nm n D = 1.7E9/cm 2 for (I D /I G ) = 0.01 Now what?

8. A Way Forward (maybe) It appears graphene is neutron damage resistant, final tests are needed Traditional silicon detectors are sensitive to neutron damage and are well studied No study has yet examined GFET response changes to neutron damage Particularly, changes to graphene response time and Dirac curve due to substrate degradation

9. Preliminary Plan It has been shown that silicon FETs sensitive to fluence as low as 10 13 n/cm 2 (fast) This level of irradiation is readily achievable in the reactor Damage results in oxide charge, neutral traps, and interface traps Perform experiment using probe station (Dr. Robinson) and reactor Gregory, B.L., “Neutron Damage Annealing in Silicon n-Channel Junction Field Effect Transistors”, IEEE Transactions on Nuclear Science, Vol. 19, Issue 3, June 1972, pp 476-497. Witteles, A.A., “Neutron Radiation Effects on MOS Fets: Theory and Experiment” IEEE Transactions on Nuclear Science, Vol. 15, Issue 6, December 1968, pp 126-132. Haider, F., et al., “The Mechanism of MOSFET Damage Induced by Neutron Radiation Resulting from D-T Fusion Reaction” Gadjah Mada University, Department of Physics Engineering.