Ultrasensitive broadband position-sensitive detector based on graphitic carbon nitride

As a typical two-dimensional material, graphitic carbon nitride (g-CN) has attracted great interest because of its distinctive electronic, optical, and catalytic properties. However, the absence of a feasible route toward large-area and high-quality films hinders its development in optoelectronics. Herein, high-quality g-CN films have been grown on Si substrate via a vapor-phase transport-assisted condensation method. The g-CN/Si heterojunction shows an obvious response to ultraviolet–visible-near infrared photons with a responsivity of 133 A·W⁻¹, which is two orders of magnitude higher than the best value ever reported for g-CN photodetectors. A position-sensitive detector (PSD) has been developed using the lateral photovoltaic effect of the g-CN/Si heterojunction. The PSD shows a wide response spectrum ranging from 300 to 1,100 nm, and a position sensitivity and rise/decay time of 395 mV·mm⁻¹ and 3.1/50 μs, respectively. Moreover, the application of the g-CN/Si heterojunction photodetector in trajectory tracking and acoustic detection has been realized for the first time. This work unveils the potential of g-CN for large-area photodetectors, and prospects for their applications in trajectory tracking and acoustic detection.