A near-infrared photodetector based on carbon nanotube transistors exhibits ultra-low dark current through field-modulated charge carrier transport.

Near-infrared photodetectors (NIR PDs) are devices that convert infrared light signals, which are widely used in military and civilian applications, into electrical signals. However, a common problem associated with PDs is a high dark current. Interestingly, gate voltage can regulate carrier migration in the channels. In this study, a PbS quantum dot heterojunction combined with a carbon nanotube (CNT) field effect transistor (FET) is designed and described. Significantly, this NIR PD achieves field-modulated carrier transport in a CNT transistor, in which the dark current is effectively regulated by the gate voltage. In this PD, an ultra-low dark current of 8 pA is obtained by gate voltage regulation. Moreover, the device shows a fast response speed of 6.5 ms and a high normalized detectivity of 4.75 × 10 Jones at 0.085 W cm power density and -0.2 V bias voltage. Overall, this work details a novel strategy for the fabrication of a PD with an ultra-low dark current based on a FET.