Researchers from the Chinese Academy of Sciences have fabricated a graphene-based transistor with a Schottky emitter - a silicon-graphene-germanium transistor. Using a semiconductor membrane and graphene transfer, the team stacked three materials including an n-type top single-crystal Si membrane, a middle single-layer graphene (Gr) and an n-type bottom Ge substrate.

A vertical silicon-graphene-germanium transistor inageDevice design and fabrication. Image credit: Nature Communications

The team explained that compared with previous tunnel emitters, the on-current of the Si-Gr Schottky emitter shows the maximum on-current and the smallest capacitance, leading to a delay time more than 1,000 times shorter. Thus, the alpha cut-off frequency of the transistor is expected to increase from about 1 MHz by using the previous tunnel emitters to above 1 GHz by using the current Schottky emitter. THz operation is expected using a compact model of an ideal device.

Pending further attention, the vertical semiconductor-graphene-semiconductor transistor is expected to be promising for high-speed applications in future 3D monolithic integration because of the advantages of atomic thickness, high carrier mobility, and the high feasibility of a Schottky emitter.

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