Self-powered CdS nanorods/planar-Si photodetector and its performance optimization by fully developing pyro-phototronic effect

Abstract

Self-powered performance is a crucial aspect of photodetectors (PDs) as it allows them to function without the need for external power sources. PDs with excellent broadband self-powered property are dependable, cost-effective, and possess high-efficiency photoelectric conversion, making them suitable for various applications. In this manuscript, a simple and low-cost hydrothermal synthesis method is employed to directly deposit cadmium sulfide (CdS) nanorods onto planar silicon (Si) substrate, resulting in a self-powered PD that incorporates a n-CdS nanorods/p-Si heterostructure. Outstanding photoresponses are observed for the PD in the range of 405∼1064 nm and open circuit voltages (Vocs) are significant, proving its prominent broadband self-powered performance. The maximum responsivity (R) and detectivity (D) are 3.92 mA/W and 7.91 × 108 Jones at zero bias, respectively. Besides, as the CdS nanorods grown on the planar Si surface exhibit superior c-axis orientation, the pyroelectric field caused by temperature variation could significantly enhance carrier transport and separation behavior in the heterojunction. Therefore, the optimal R of 64.8 mA/W and D of 1.31 × 1010 Jones are achieved, with an argument of 3450.5%, as well as a fast response time of 190.8/298.4 μs. Furthermore, the light response wavelength extends to 1550 nm, covering visible light to near-infrared, far beyond the spectral limitations of the heterojunction. This high-performance broadband self-powered PD is expected to show great potentials in various applications.