A Micro Broadband Photodetector Based on Single Wall Carbon Nanotubes-Graphene Heterojunction

A room-temperature broadband (visible to near infrared spectrum) photodetector based on single wall carbon nanotubes (SWCNTs) and graphene heterojunction was fabricated in this work, by drop-casting the SWCNTs suspension onto the graphene field-effect transistor with the buried-gate electrode. A high photoresponsivity of 109 A/W and a fast photoresponse speed of 2.9 ms were obtained within the visible region based on the photogating effect. This high gain mechanism leads to a high photoconductive gain (9.1 106). In addition, the photodetector exhibits a photoresponsivity of 51.5 A/W at 940 nm, indicating a wide spectrum detection capability. Moreover, a higher photoresponsivity can be obtained by tuning the source-drain and gate bias voltages. This approach provides an easy and feasible way to achieve broadband heterojunction photodetectors with high-performance.