▎ 摘　　要

NOVELTY - A FET has a graphene layer (12) provided on a substrate (10) made of Sic and a source electrode and a drain electrode (26), each electrode (24) is provided on the graphene layer. A first and a second gate electrode (20) are provided on the graphene layer. The first gate electrode is placed closer to the source electrode and the second m gate electrode is placed closer to the drain electrode. The second gate electrode receives a reference bias higher than a gate bias supplied to the first gate electrode. An intermediate electrode (28) is provided between the two gate electrodes. USE - Field effect transistor (FET) used for semiconductor devices. ADVANTAGE - The second gate electrode effectively suppresses the hole injection into the channel beneath the first gate electrode, which effectively suppress the drain conductance and enhance the high frequency performance of the FET. The aluminum oxide film effectively suppresses the gate leak current, which enhances the performance of the FET. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method to produce a field effect transistor (FET) having a graphene layer as a channel layer. DESCRIPTION OF DRAWING(S) - The drawing shows the structural view of the processes to produce the FET. Substrate (10) Graphene layer (12) Gate electrode (20) Electrode (24) Drain electrode (26) Intermediate electrode (28)