Self-Powered ZnO@PdTe 2 /Si Heterojunction Photodetector with an Ultrafast Response for Color Imaging and Optical Communication.

Broadband photodetectors have attracted much attention due to their multispectral response properties and show great potential in the fields of optical sensing, multispectral imaging, and optical communications. Palladium telluride (PdTe 2 ) is highly competitive in broadband detection due to its tunable bandgap and nonlinear optical properties. However, the low response speed hinders further improvement in the performance of PdTe 2 -based broadband photodetectors. In this work, we present island-type ZnO@PdTe 2 composites on Si as a heterojunction photodetector exhibiting highly sensitive photodetection capabilities in a wide band from the solar-blind region (254 nm) to the short-infrared (1.55 μm). Due to the island-type morphology of the ZnO@PdTe 2 composites effectively enhancing light absorption and the ZnO@PdTe 2 /Si stacks forming a type-II heterojunction accelerating carrier separation, the devices have an ultrafast response (1.58/1.34 μs), a detectivity of up to 1.56 × 10 13 Jones, and a sensitivity of up to 10 7 cm 2 /W. A triple-channel color imaging system and a dual-channel data transmission system were developed based on the excellent and stable performance of the device. This study demonstrates the great potential of ZnO@PdTe 2 /Si vertical heterojunction photodetectors for high-speed, wide-band, multiscenario optical communication.