Multi-Mechanism Driven Ta2NiSe5–Graphene Heterojunction for Ultrabroadband Detection from Visible to Terahertz Spectrum

Abstract

Ultrabroadband photodetectors are essential for applications such as biomedical imaging, environmental assessment, optical data transmission, gas detection, and security monitoring. However, traditional semiconductor detectors are typically limited to detection within a single spectral range, and achieving ultrabroadband detection often requires integrating multiple detectors. This is particularly challenging in the terahertz range, where detection is constrained by high dark currents and the need for cryogenic cooling. As a result, expanding the detection range has become a critical focus in optoelectronic development. In this study, we successfully demonstrated ultrabroadband detection from the visible to terahertz spectrum at room temperature using a heterojunction formed by Ta₂NiSe₅ and graphene, driven by multiple physical mechanisms. The detector leverages the combined effects of photoexcited electron–hole pairs and the photothermal response triggered by the asymmetry of the heterojunction, achieving responsivities of 4.8 mA/W at 638 nm, 3.8 mA/W at 1550 nm, 42.9 mA/W at 0.12 THz, and 14.6 mA/W at 0.3 THz. Additionally, the device achieves NEP values as low as 7 pW/Hz^1/2 at 0.12 THz and 23 pW/Hz^1/2 at 0.3 THz, with a response time of 7.4 μs at 0.12 THz. Our findings demonstrate a novel approach to ultrabroadband detection, achieving high sensitivity and fast response by leveraging multiple physical mechanisms. This work opens new avenues for the future development of optoelectronic detection technologies.