UW-Madison researchers have leveraged semiconductor grafting to synthesize and characterize a lattice-mismatched single-crystalline GaAs/GeSn MQW/Ge n-i-p heterojunction. Scanning transmission electron microscopy studies showed the grafted GaAs/GeSn-MQW heterointerfaces were atomically clean, without any significant atomic intermixing. Photodiodes were then fabricated from both grafted GaAs/GeSn-MQW/Ge and reference epitaxial Ge/GeSn-MQW/Ge heterojunctions. Compared to conventional epitaxial photodiodes, the tailored electronic band alignment and optical light distribution in the grafted GaAs/GeSn-MQW/Ge heterojunction photodiode result in distinct device behaviors, including an extended detection wavelength range from the visible to near-infrared. This results in a device capable of running in visible light detection mode with negative bias and in near IR mode with a positive bias, in contrast to existing photodetectors that can only measure one or the other. Moreover, the photoresponsivity exhibited remarkable enhancement, achieving approximately a sevenfold increase in the VIS range and a threefold improvement in the NIR range compared to the reference epitaxial photodiode. The dark current density, a key metric for industrial devices, was also at least five orders of magnitude lower than state-of-the-art GeSn photodiodes.