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In this work, the epitaxial graphene channel formed on 3C-SiC grown on a Si substrate backgate transistor was designed, fabricated and characterized for electronic and optoelectronic applications. Even though a significant amount of the gate leakage current is observed, the experimental results show the device works as an n-type transistor as well as an infrared photovoltaic transistor with the backgate modulation. The observation of the ambipolar behavior verifies the unique property of the graphene layers. The epitaxial graphene is believed to be unintentionally p-type with the Fermi level offset around +0.11∼+0.12 V at the Dirac point. The drain saturated current of the graphene channel transistors is on the order of mA/mm. The photo-generated current can be achieved up to almost 20nA, corresponding to 0.06 mA/W in photo-responsivity at 0.5-V drain-source bias voltage and 0.5-V gate voltage. The backgate voltage tuning spectral characteristic is also demonstrated. The graphene based transistors have a potential application in infrared detection.

We have fabricated and characterized the field effect transistors having epitaxial-graphene channel grown on Si substrates. Epitaxial graphene is usually formed on SiC substrates by ultrahigh-vacuum (UHV) annealing. We used an approach to grow 3C-SiC(111) on Si substrates and subsequently to anneal it in UHV to make few layers of graphene on the sample surface. Backgate transistors using the SiC layer as a gate insulator was characterized. Although significant gate leakage current is observed, the drain current modulation by the gate voltage is confirmed by extracting the channel current from the total drain current. The drain saturation current of the graphene-channel transistors is in the order of mA/mm due to the large contact resistance that should be minimized in future study.