# How many defects in graphene would kill its conductivity?

## Main Question or Discussion Point

I had a random idea about the effect of cosmic rays on graphene's conductivity. I found out that cosmic rays would create defects in graphene over time. How many of these defects would significantly reduce the conductivity of graphene? How do I go about calculating how much time the graphene should be exposed to cosmic rays to significantly affect conductivity?

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UltrafastPED
Gold Member
You can calculate this yourself; you will need the cosmic ray flux, the damage rate of graphene for cosmic rays, and the effect of defects upon graphene conductivity.

Summary: http://en.wikipedia.org/wiki/Graphene#Electronic

Some experimental work: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.246803

Some theory: http://arxiv.org/abs/0706.2968
and http://arxiv.org/pdf/0706.1888.pdf?origin=publication_detail

Cosmic ray flux: http://en.wikipedia.org/wiki/Cosmic_ray

Study of radiation effects upon graphene: http://www.nanowerk.com/spotlight/spotid=30443.php

Let us know how you plan to proceed!

I'm sorry, but all these links refer to articles that seem to be really far out of my current knowledge reach. Could you please help me out?

I understand that cosmic ray flux is a unit which quantifies the amount of particles passing per unit area.

"Transport in undoped graphene is related to percolating current patterns in the networks of N-type and P-type regions reflecting the strong bipolar charge density fluctuations. Transmissions of the P-N junctions, though small, are vital in establishing the macroscopic conductivity."

I'm not sure what exactly this means, but I know that in semiconductors, N-type junctions have more electrons and P-type junctions have more electron holes and this controls the current flow between them. Could you please explain what the statement means?

UltrafastPED