This paper reports a significant advancement in the design of 2D photodetectors by enhancing both responsivity and response speed in a WSe₂/Ta₂NiSe₅ heterostructure. The photogating effect, which is a dominant mechanism in most high-responsivity 2D material photodetectors, typically results in slow response speeds. However, the authors demonstrate that photogating-assisted tunneling can synergistically enhance photocarrier multiplication and carrier acceleration under an electrical field, thereby overcoming the trade-off between responsivity and speed. The key findings include: 1. **Enhanced Responsivity and Speed**: The device achieves a responsivity of over 10^4 A/W and a response time of approximately 1 μs, significantly improving upon existing 2D photodetectors. 2. **Low Power Consumption**: The device operates with low power consumption, on the order of nW, making it suitable for various applications. 3. **Polarization Detection**: The device exhibits polarization-dependent photoresponse, allowing for wavelength discrimination using a two-electrode planar structure. 4. **Bias-Tunable Transport**: The device's performance can be tuned by adjusting the source-drain voltages, providing a flexible platform for advanced photodetector applications. The study highlights the potential of 2D materials in achieving high responsivity, fast response, and polarization detection, making it a promising candidate for next-generation photodetectors in applications such as miniaturized spectroscopy, spectral imaging, and object identification.This paper reports a significant advancement in the design of 2D photodetectors by enhancing both responsivity and response speed in a WSe₂/Ta₂NiSe₅ heterostructure. The photogating effect, which is a dominant mechanism in most high-responsivity 2D material photodetectors, typically results in slow response speeds. However, the authors demonstrate that photogating-assisted tunneling can synergistically enhance photocarrier multiplication and carrier acceleration under an electrical field, thereby overcoming the trade-off between responsivity and speed. The key findings include: 1. **Enhanced Responsivity and Speed**: The device achieves a responsivity of over 10^4 A/W and a response time of approximately 1 μs, significantly improving upon existing 2D photodetectors. 2. **Low Power Consumption**: The device operates with low power consumption, on the order of nW, making it suitable for various applications. 3. **Polarization Detection**: The device exhibits polarization-dependent photoresponse, allowing for wavelength discrimination using a two-electrode planar structure. 4. **Bias-Tunable Transport**: The device's performance can be tuned by adjusting the source-drain voltages, providing a flexible platform for advanced photodetector applications. The study highlights the potential of 2D materials in achieving high responsivity, fast response, and polarization detection, making it a promising candidate for next-generation photodetectors in applications such as miniaturized spectroscopy, spectral imaging, and object identification.