Graphene Field-Effect Photodetectors on Si and GaAs substrates.

Graphene Field Effect Transistors (GFETs) have emerged as a promising technology for advanced optoelectronic applications, especially for photodetection. These photodetectors utilize graphene as a photoconductive channel to circulate photocurrent, fabricated on top of a semiconductor substrate that will use a phenomenon known as photogating to obtain a high photoconductive gain. We explore the performance of GFET photodetectors of graphene on silicon (Si) and gallium arsenide (GaAs) substrates. The photodetectors exhibit high responsivity in the range of 10⁶ A/W and the detection range of photon energy strongly depends on the bandgap property of the semiconductor materials. In addition, graphene on GaAs substrate photodetectors show a higher responsivity than those from graphene on Si substrate devices due to the direct bandgap property of GaAs semiconductors. These devices have fast response times in the range from nanosecond to microseconds. The devices show a great potential for photodetection in a wide range of wavelengths, opening avenues for diverse applications in optics, telecommunication, and sensing.