Photothermoelectric SnTe Photodetector with Broad Spectral Response and High On/Off Ratio

A broadband photodetector with high performance is highly desirable for the optoelectric and sensing application. Herein, we report a photo-thermo-electric (PTE) detector based on an ultrathin SnTe film. The (001)-oriented SnTe films with the wafer size scale are epitaxially grown on the surface of sodium chloride crystals by a scalable sputtering method. Due to the giant PTE effect under laser spot excitation on the asymmetric position between two terminals, a built-in electrical field is produced to drive bulk carriers for a self-powered photodetector, leading to a broad spectral response in the wavelength range from 404 nm to 10.6 mu m far beyond the limitation of the energy band gap. Significantly, the photodetector displays a high on/off photoswitching ratio of over 10(5) with a suppressed dark current, which is 4-5 orders of magnitude higher than that of other reported SnTe-based detectors. Under zero external bias, the device yields the highest detectivity of similar to 1.3 x 10(10) cm Hz(1/2) W-1 with a corresponding responsivity of similar to 3.9 mA W-1 and short rising/falling times of similar to 78/84 ms. Furthermore, the photodetector transferred onto the flexible template exhibits excellent mechanical flexibility over 300 bending cycles. These findings offer feasible strategies toward designing and developing low-power-consumption wearable optoelectronics with competitive performance.