2D tellurium film/pyramid-silicon heterostructure arrays for broadband photoelectric detection and imaging device

Since the invention of photodetectors, high-performance devices of various types, functions, and applications have been extensively used across diverse sectors of the economy and daily life. However, due to the limitations of the wide bandgap of silicon (Si) and the incompatibility of most near-infrared optoelectronic materials with traditional integrated circuits, the development of high-performance, broad-spectrum near-infrared detectors suitable for miniaturization and integration still faces many challenges. Van der Waals (vdW) materials have emerged as a prominent research focus in recent years owing to their unique physicochemical properties. A series of narrow-bandgap vdW materials—such as black phosphorus (BP) and palladium diselenide (PdSe2) have been successively explored for infrared photodetection. As a chalcogen element, tellurium (Te) is a p-type narrow-bandgap semiconductor, which features a distinctive one-dimensional helical chain structure. It exhibits superior electrical properties, including ultrahigh carrier mobility and thickness-dependent bandgap, which make it a promising material for next-generation electronic and optoelectronic devices. Moreover, Te has a narrow optical bandgap of ~0.35 eV and strong light-matter interaction in the NIR spectrum. Considering the limitations of silicon in infrared photodetection, Te/Si heterostructures can be anticipated to deliver a desirable broadband response.In this work, we propose a 2D Te film/pyramid-Si (Te/py-Si) heterostructure device array for NIR photodetection and imaging. Centimeter-scale Te films with different thicknesses were prepared at room temperature via magnetron sputtering. Using the mask-assisted magnetron sputtering, patterned Te films were fabricated on the surface of n-type py-Si, forming an 8×8 Te/py-Si heterostructure array. It was found that 2D Te film and py-Si can reduce the device′s reflectivity at NIR and visible light, respectively, which subsequently enhances the overall light utilization of the device. As results, the Te/py-Si heterostructure device exhibits excellent photoelectrical performance under visible and NIR light illumination. Under 980 nm illumination, the device achieves a responsivity of 6.95 mA/W, photocurrent on/off ratio of 4.1×102, and specific detectivity of 1.36×109 Jones. Furthermore, both the individual pixels photodetector and the photodetector array realize the visible and NIR photoelectric imaging with distinct and sharp contours, indicating the promising application of the Te/py-Si photodetectors in future optoelectronic imaging. This work not only presents a high-performance photodetector but also provides a new and versatile route for fabricating mixed-dimensional van der Waals heterostructures. By combining the advantages of 2D materials with microstructured Si substrates in a scalable process, it paves the way for implementing these advanced photodetectors in next-generation optoelectronic systems, including compact NIR cameras and integrated optical sensors.