Christophe Caillier, Dong-Keun Ki, Yuliya Lisunova, Iaroslav Gaponenko, Patrycja Paruch, Alberto F. Morpurgo
To minimize drifts caused by uncontrolled material absorption, graphene is often investigated under vacuum. Here we report an entirely unexpected phenomenon occurring in vacuum systems, namely strong n-doping of graphene due to chemical species generated by common ion high-vacuum gauges. The effect -- reversible upon exposing graphene to air -- is strong, as doping rates can largely exceed 10^12 cm^(-2)/hour, depending on pressure and relative position of the gauge and graphene. It is important to be aware of the phenomenon, as its basic manifestation can be mistakenly interpreted as due to vacuum-induced desorption of p-dopants.
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http://arxiv.org/abs/1302.5318
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