Optoelectronic application of multi-layer epitaxial graphene on a Si substrate

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 20 nA, 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.