Modeling of Graphene-Semiconductor Heterostructure Photodetectors

Graphene-based field-effect transistors are a promising technology for high-sensitivity photo-detection. However, the performance of graphene photodetectors is limited by the low photon absorption and the ultrafast carrier lifetime. To overcome these issues, the use of hybrid graphene-semiconductor structures has been employed. The defining features of these structures are a semiconductor thin film, used for photon absorption, and graphene which is utilized for the charge transport channel due to its ultrafast carrier mobility. With the interest in the development of these devices, it is important to understand how the absorber layer and graphene layer interact with incident light to create a strong photo-response. A model of the photoconductive mechanism is proposed showing that the photo-response for the devices is the modulation of the conducting surface due to the changing of the surface depletion layer. As shown by this simulation, several factors, including the doping concentration of the absorbing material, thickness of the absorbing material, and the size of the photodetectors have a strong impact on the performance of the graphene photodetectors.