Photodetectors are receiving increasing attention because of their widely important applications. Therefore, developing broadband high-performance photodetectors using new materials that can function at room temperature has become increasingly important. As a functional material, tin telluride (SnTe), has been widely studied as a thermoelectric material. Furthermore, because of its narrow bandgap, it can be used as a novel infrared photodetector material. In this study, a large-area SnTe nanofilm with controllable thickness was deposited onto a quartz substrate using magnetron sputtering and was used to fabricate a photodetector. The device exhibited a photoelectric response over a broad spectral range of 400-1050 nm. In the near-infrared band of 940 nm, the detectivity (D*) and responsivity (R) of the photodetector were 3.46×1011 cmHz1/2w-1 and 1.71 A/W, respectively, at an optical power density of 0.2 mWcm-2. As the thickness of the SnTe nanofilm increased, a transition from semiconducting to metallic properties was experimentally observed for the first time. The large-area (2.5cm × 2.5cm) high-performance nanofilms show important potential for application in infrared focal plane array (FPA) detectors.