Trap Assisted Bulk Silicon Photodetector with High Photoconductive Gain, Low Noise, and Fast Response by Ag Hyperdoping

Silicon-based photoconductors, with their low cost, high sensitivity, and complementary metal-oxide-semiconductor (CMOS) compatibility, have great potential for high-resolution imaging, light-activated switching, and single-photon counting. However, they usually suffer from a large dark leakage current and a long response time, which greatly limits their applications. Here, a high-performance bulk silicon photodetector is fabricated working at room temperature with a broad spectral response range from 300 to 1200 nm through silver (Ag) hyperdoping. The detector shows a low dark current of 3.8 x 10(-7) A cm(-2) and a high external quantum efficiency of 266.0% for 800 nm at -1 V reverse bias, indicating a photoconductive gain. Moreover, the Si:Ag photodetector has a very low noise and a high detectivity (=1.84 x 10(12) Jones at -1 V), and meanwhile exhibits a rapid response speed with the rise time of 12.5 mu s and fall time of 15.9 mu s. By combining with the deep level transient spectrum measurements, it is believed that the operating mechanism of the detector is based on the electron traps with an average energy level of E-c- 0.28 eV induced by the Ag hyperdoping. These results are of significance for the fabrication of silicon-based photodetectors with high performances.