Graphene-Diamond Heterostructures: Toward All-Carbon Devices with Enhanced Electrical Properties

A variety of field effect transistors (FETs) with two types of graphene-diamond (G-D) heterostructures have been fabricated. The results indicate that the transferred G-D FETs exhibit bipolar output characteristics, characterized by a transfer curve resembling a classic V-shape. In contrast, the in situ catalyzed G-D FETs demonstrate a more complex output behavior. Notably, linear ohmic contact characteristics are established between Pd/Ti/Au contacts and the in situ G-D heterostructure without requiring additional postannealing treatment. An unprecedentedly low specific contact resistivity of 1.4 × 10–7 Ω cm2 has been achieved. For the in situ catalyzed G-D FETs, top-gated FETs display unipolar output characteristics with an impressive current density reaching 106 A cm–2. Conversely, ring-gated FETs exhibit bipolar output characteristics, featuring a Dirac point at a voltage of 3 V. For certain FETs lacking gate modulation, approximately 18 nm-thick graphene layers situated beneath the gate oxide as the channel. This study paves new pathways for advancements in graphene-based devices or all-carbon electronics.