# How many defects in graphene would kill its conductivity?

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1. Mar 25, 2014

### Droctagonopus

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?

2. Mar 25, 2014

### UltrafastPED

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!

3. Mar 25, 2014

### Droctagonopus

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?

4. Mar 25, 2014

### UltrafastPED

Sorry, but nobody is going to spend hours or days to work out your idea.

My first sentence outlines the process required; the articles provide the detailed information required.

That's my ten minutes - I'm gone.