Mixed-Dimensional PtSe2/Bi2Te3/Pyramid Si Heterojunction with a Light-Trapping Structure for Highly Sensitive Ultrabroadband Photodetection

Broadband photodetectors have garnered widespread attention in the realm of modern optoelectronic devices and systems due to their pivotal role in various applications. Topological insulators have emerged as promising candidates for broadband photodetection by leveraging their distinct electrical and optoelectrical properties. Here, we report the successful fabrication of a topological insulator Bi2Te3/pyramidal Si heterojunction, incorporating a top two-dimensional PtSe2 layer for highly sensitive broadband photodetection and image sensing. Owing to the light trapping structure of pyramidal Si and the broad light absorption spectrum of the mixed-dimensional hybrid structure, the photodetector exhibits a self-powered ultrabroadband response range spanning of 265 nm to 10.6 μm, with a responsivity of up to 620 mW/A, a specific detectivity of 1.37 × 1012 cm Hz1/2 W–1, and a fast response speed of 0.45/18 μs. Additionally, the integrated PtSe2/Bi2Te3/pyramid Si detector array has demonstrated exceptional broadband imaging capabilities. This study provides a feasible pathway for realizing highly sensitive broadband photodetection and imaging applications.