Download Radiation Damage Quick Study

Radiation Damage Quick Study
Edward Cazalas
3/27/13
Goal
Determine…
• What is damage?
• How is damage quantified?
• How much damage previously observed in graphene?
• Now what?
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.
How is Damage Quantified?
TEM
(Tunneling electron microscope)
80 keV (300 keV ~107 e-/nm2 inset)
Raman Spectroscopy
a)
b)
c)
Single layer pristine suspended graphene
1E18 ions/cm2
1E19 ions/cm2
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.
Previous Study - Proton Irradiation
2 MeV p+
6E18 ions/cm2
1E18 ions/cm2
1E17 ions/cm2
Threshold at 1E16 ions/cm2
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+
1E19 ions/cm2
6E18 ions/cm2
1E18 ions/cm2
1E18 ions/cm2
1E17 ions/cm2
Supported
Suspended
Electronically stimulated desorption – bond breaking
Substrate allows additional modes of energy dissipation
Coulombic interaction
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.
Neutron Damage
Damage occurs through neutron-carbon ejection (elastic scattering)
Carbon neutron σ ≈ 1b = 1E-24 cm2
Neutron Fluence = 1E16 n/cm2
Graphene atomic surface density =
3.8E15/cm2
Carbon ejection surface density =
3.8E7/cm2
nD(cm-2) = 7.3E9 E4(ID/IG)
nD = 1.7E9/cm2
E = 2.2 eV for 562 nm
for (ID/IG) = 0.01
Now what?
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.
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
Preliminary Plan
• It has been shown that silicon FETs sensitive to fluence as
low as 1013 n/cm2 (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.