This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We have fabricated transistor structures using fluorinated single-layer graphene flakes and studied their electronic properties at different temperatures. Compared with pristine graphene, fluorinated graphene has very large and strongly temperature dependent resistance in the electro-neutrality region. We show that fluorination creates a mobility gap in graphene's spectrum where electron transport takes place via localised electron states.We are grateful to A. V. Shytov for useful discussions and
A. A. Kozikov for help with measurements, and to EPSRC
for funding
