Damage-free hydrogenation of graphene via ion energy control in plasma

We proposed appropriate plasma conditions for hydrogenation of graphene without structural defect formation using ion energy analysis. Graphene sheets were exposed to plasma having H3+ ions with energies of 3.45, 5.35, and 7.45 eV. Only the specimen treated by the plasma with the lowest energy was converted back to graphene by thermal annealing, and the others showed irreversible characteristics because of the vacancy defects generated by high-energy ions. Finally, we demonstrated the reversible characteristic in graphene field-effect transistor using the plasma with appropriate ion energy and Joule heating, indicating that damage induced by plasma was negligible.