▎ 摘　　要

Tuning of the Fermi level is investigated in graphene channels using two in-plane gates with significantly different-sized isolating gaps. While the n-type tuning was achievable in both schemes, the wide-gap device had an enhanced minimum drain current and less prominent current modulation than the narrow-gap device. In addition, further p-type tuning was not observed in the wide-gap device at negative gate biases. These phenomena indicated that both devices had distinct field-strength dependences and Fermi level tuning effects, which may be critical for the practical design of devices. (C) 2014 AIP Publishing LLC.